diff --git a/e2e/preview/components/test_gpt35_generator.py b/e2e/preview/components/test_gpt35_generator.py
new file mode 100644
index 0000000000..c70b8033f5
--- /dev/null
+++ b/e2e/preview/components/test_gpt35_generator.py
@@ -0,0 +1,86 @@
+import os
+import pytest
+import openai
+from haystack.preview.components.generators.openai.gpt35 import GPT35Generator
+
+
+@pytest.mark.skipif(
+    not os.environ.get("OPENAI_API_KEY", None),
+    reason="Export an env var called OPENAI_API_KEY containing the OpenAI API key to run this test.",
+)
+def test_gpt35_generator_run():
+    component = GPT35Generator(api_key=os.environ.get("OPENAI_API_KEY"), n=1)
+    results = component.run(prompts=["What's the capital of France?", "What's the capital of Germany?"])
+
+    assert len(results["replies"]) == 2
+    assert len(results["replies"][0]) == 1
+    assert "Paris" in results["replies"][0][0]
+    assert len(results["replies"][1]) == 1
+    assert "Berlin" in results["replies"][1][0]
+
+    assert len(results["metadata"]) == 2
+    assert len(results["metadata"][0]) == 1
+    assert "gpt-3.5-turbo" in results["metadata"][0][0]["model"]
+    assert "stop" == results["metadata"][0][0]["finish_reason"]
+    assert len(results["metadata"][1]) == 1
+    assert "gpt-3.5-turbo" in results["metadata"][1][0]["model"]
+    assert "stop" == results["metadata"][1][0]["finish_reason"]
+
+
+@pytest.mark.skipif(
+    not os.environ.get("OPENAI_API_KEY", None),
+    reason="Export an env var called OPENAI_API_KEY containing the OpenAI API key to run this test.",
+)
+def test_gpt35_generator_run_wrong_model_name():
+    component = GPT35Generator(model_name="something-obviously-wrong", api_key=os.environ.get("OPENAI_API_KEY"), n=1)
+    with pytest.raises(openai.InvalidRequestError, match="The model `something-obviously-wrong` does not exist"):
+        component.run(prompts=["What's the capital of France?"])
+
+
+@pytest.mark.skipif(
+    not os.environ.get("OPENAI_API_KEY", None),
+    reason="Export an env var called OPENAI_API_KEY containing the OpenAI API key to run this test.",
+)
+def test_gpt35_generator_run_above_context_length():
+    component = GPT35Generator(api_key=os.environ.get("OPENAI_API_KEY"), n=1)
+    with pytest.raises(
+        openai.InvalidRequestError,
+        match="This model's maximum context length is 4097 tokens. However, your messages resulted in 70008 tokens. "
+        "Please reduce the length of the messages.",
+    ):
+        component.run(prompts=["What's the capital of France? " * 10_000])
+
+
+@pytest.mark.skipif(
+    not os.environ.get("OPENAI_API_KEY", None),
+    reason="Export an env var called OPENAI_API_KEY containing the OpenAI API key to run this test.",
+)
+def test_gpt35_generator_run_streaming():
+    class Callback:
+        def __init__(self):
+            self.responses = ""
+
+        def __call__(self, chunk):
+            self.responses += chunk.choices[0].delta.content if chunk.choices[0].delta else ""
+            return chunk
+
+    callback = Callback()
+    component = GPT35Generator(os.environ.get("OPENAI_API_KEY"), streaming_callback=callback, n=1)
+    results = component.run(prompts=["What's the capital of France?", "What's the capital of Germany?"])
+
+    assert len(results["replies"]) == 2
+    assert len(results["replies"][0]) == 1
+    assert "Paris" in results["replies"][0][0]
+    assert len(results["replies"][1]) == 1
+    assert "Berlin" in results["replies"][1][0]
+
+    assert callback.responses == results["replies"][0][0] + results["replies"][1][0]
+
+    assert len(results["metadata"]) == 2
+    assert len(results["metadata"][0]) == 1
+
+    assert "gpt-3.5-turbo" in results["metadata"][0][0]["model"]
+    assert "stop" == results["metadata"][0][0]["finish_reason"]
+    assert len(results["metadata"][1]) == 1
+    assert "gpt-3.5-turbo" in results["metadata"][1][0]["model"]
+    assert "stop" == results["metadata"][1][0]["finish_reason"]
diff --git a/haystack/preview/components/generators/openai/_helpers.py b/haystack/preview/components/generators/openai/_helpers.py
deleted file mode 100644
index 946901b644..0000000000
--- a/haystack/preview/components/generators/openai/_helpers.py
+++ /dev/null
@@ -1,33 +0,0 @@
-import logging
-
-from haystack.preview.lazy_imports import LazyImport
-
-with LazyImport("Run 'pip install tiktoken'") as tiktoken_import:
-    import tiktoken
-
-
-logger = logging.getLogger(__name__)
-
-
-def enforce_token_limit(prompt: str, tokenizer: "tiktoken.Encoding", max_tokens_limit: int) -> str:
-    """
-    Ensure that the length of the prompt is within the max tokens limit of the model.
-    If needed, truncate the prompt text so that it fits within the limit.
-
-    :param prompt: Prompt text to be sent to the generative model.
-    :param tokenizer: The tokenizer used to encode the prompt.
-    :param max_tokens_limit: The max tokens limit of the model.
-    :return: The prompt text that fits within the max tokens limit of the model.
-    """
-    tiktoken_import.check()
-    tokens = tokenizer.encode(prompt)
-    tokens_count = len(tokens)
-    if tokens_count > max_tokens_limit:
-        logger.warning(
-            "The prompt has been truncated from %s tokens to %s tokens to fit within the max token limit. "
-            "Reduce the length of the prompt to prevent it from being cut off.",
-            tokens_count,
-            max_tokens_limit,
-        )
-        prompt = tokenizer.decode(tokens[:max_tokens_limit])
-    return prompt
diff --git a/haystack/preview/components/generators/openai/gpt35.py b/haystack/preview/components/generators/openai/gpt35.py
new file mode 100644
index 0000000000..e58b1ffa05
--- /dev/null
+++ b/haystack/preview/components/generators/openai/gpt35.py
@@ -0,0 +1,213 @@
+from typing import Optional, List, Callable, Dict, Any
+
+import sys
+import logging
+from dataclasses import dataclass, asdict
+
+import openai
+
+from haystack.preview import component, default_from_dict, default_to_dict, DeserializationError
+
+
+logger = logging.getLogger(__name__)
+
+
+@dataclass
+class _ChatMessage:
+    content: str
+    role: str
+
+
+def default_streaming_callback(chunk):
+    """
+    Default callback function for streaming responses from OpenAI API.
+    Prints the tokens of the first completion to stdout as soon as they are received and returns the chunk unchanged.
+    """
+    if hasattr(chunk.choices[0].delta, "content"):
+        print(chunk.choices[0].delta.content, flush=True, end="")
+    return chunk
+
+
+@component
+class GPT35Generator:
+    """
+    LLM Generator compatible with GPT3.5 (ChatGPT) large language models.
+
+    Queries the LLM using OpenAI's API. Invocations are made using OpenAI SDK ('openai' package)
+    See [OpenAI GPT3.5 API](https://platform.openai.com/docs/guides/chat) for more details.
+    """
+
+    def __init__(
+        self,
+        api_key: str,
+        model_name: str = "gpt-3.5-turbo",
+        system_prompt: Optional[str] = None,
+        streaming_callback: Optional[Callable] = None,
+        api_base_url: str = "https://api.openai.com/v1",
+        **kwargs,
+    ):
+        """
+        Creates an instance of GPT35Generator for OpenAI's GPT-3.5 model.
+
+        :param api_key: The OpenAI API key.
+        :param model_name: The name of the model to use.
+        :param system_prompt: An additional message to be sent to the LLM at the beginning of each conversation.
+            Typically, a conversation is formatted with a system message first, followed by alternating messages from
+            the 'user' (the "queries") and the 'assistant' (the "responses"). The system message helps set the behavior
+            of the assistant. For example, you can modify the personality of the assistant or provide specific
+            instructions about how it should behave throughout the conversation.
+        :param streaming_callback: A callback function that is called when a new token is received from the stream.
+            The callback function should accept two parameters: the token received from the stream and **kwargs.
+            The callback function should return the token to be sent to the stream. If the callback function is not
+            provided, the token is printed to stdout.
+        :param api_base_url: The OpenAI API Base url, defaults to `https://api.openai.com/v1`.
+        :param kwargs: Other parameters to use for the model. These parameters are all sent directly to the OpenAI
+            endpoint. See OpenAI [documentation](https://platform.openai.com/docs/api-reference/chat) for more details.
+            Some of the supported parameters:
+            - `max_tokens`: The maximum number of tokens the output text can have.
+            - `temperature`: What sampling temperature to use. Higher values mean the model will take more risks.
+                Try 0.9 for more creative applications, and 0 (argmax sampling) for ones with a well-defined answer.
+            - `top_p`: An alternative to sampling with temperature, called nucleus sampling, where the model
+                considers the results of the tokens with top_p probability mass. So 0.1 means only the tokens
+                comprising the top 10% probability mass are considered.
+            - `n`: How many completions to generate for each prompt. For example, if the LLM gets 3 prompts and n is 2,
+                it will generate two completions for each of the three prompts, ending up with 6 completions in total.
+            - `stop`: One or more sequences after which the LLM should stop generating tokens.
+            - `presence_penalty`: What penalty to apply if a token is already present at all. Bigger values mean
+                the model will be less likely to repeat the same token in the text.
+            - `frequency_penalty`: What penalty to apply if a token has already been generated in the text.
+                Bigger values mean the model will be less likely to repeat the same token in the text.
+            - `logit_bias`: Add a logit bias to specific tokens. The keys of the dictionary are tokens and the
+                values are the bias to add to that token.
+        """
+        self.api_key = api_key
+        self.model_name = model_name
+        self.system_prompt = system_prompt
+        self.model_parameters = kwargs
+        self.streaming_callback = streaming_callback
+        self.api_base_url = api_base_url
+
+    def to_dict(self) -> Dict[str, Any]:
+        """
+        Serialize this component to a dictionary.
+        """
+        if self.streaming_callback:
+            module = self.streaming_callback.__module__
+            if module == "builtins":
+                callback_name = self.streaming_callback.__name__
+            else:
+                callback_name = f"{module}.{self.streaming_callback.__name__}"
+        else:
+            callback_name = None
+
+        return default_to_dict(
+            self,
+            api_key=self.api_key,
+            model_name=self.model_name,
+            system_prompt=self.system_prompt,
+            streaming_callback=callback_name,
+            api_base_url=self.api_base_url,
+            **self.model_parameters,
+        )
+
+    @classmethod
+    def from_dict(cls, data: Dict[str, Any]) -> "GPT35Generator":
+        """
+        Deserialize this component from a dictionary.
+        """
+        init_params = data.get("init_parameters", {})
+        streaming_callback = None
+        if "streaming_callback" in init_params:
+            parts = init_params["streaming_callback"].split(".")
+            module_name = ".".join(parts[:-1])
+            function_name = parts[-1]
+            module = sys.modules.get(module_name, None)
+            if not module:
+                raise DeserializationError(f"Could not locate the module of the streaming callback: {module_name}")
+            streaming_callback = getattr(module, function_name, None)
+            if not streaming_callback:
+                raise DeserializationError(f"Could not locate the streaming callback: {function_name}")
+            data["init_parameters"]["streaming_callback"] = streaming_callback
+        return default_from_dict(cls, data)
+
+    @component.output_types(replies=List[List[str]], metadata=List[Dict[str, Any]])
+    def run(self, prompts: List[str]):
+        """
+        Queries the LLM with the prompts to produce replies.
+
+        :param prompts: The prompts to be sent to the generative model.
+        """
+        chats = []
+        for prompt in prompts:
+            message = _ChatMessage(content=prompt, role="user")
+            if self.system_prompt:
+                chats.append([_ChatMessage(content=self.system_prompt, role="system"), message])
+            else:
+                chats.append([message])
+
+        all_replies, all_metadata = [], []
+        for chat in chats:
+            completion = openai.ChatCompletion.create(
+                model=self.model_name,
+                api_key=self.api_key,
+                messages=[asdict(message) for message in chat],
+                stream=self.streaming_callback is not None,
+                **self.model_parameters,
+            )
+
+            replies: List[str]
+            metadata: List[Dict[str, Any]]
+            if self.streaming_callback:
+                replies_dict = {}
+                metadata_dict: Dict[str, Dict[str, Any]] = {}
+                for chunk in completion:
+                    chunk = self.streaming_callback(chunk)
+                    for choice in chunk.choices:
+                        if choice.index not in replies_dict:
+                            replies_dict[choice.index] = ""
+                            metadata_dict[choice.index] = {}
+
+                        if hasattr(choice.delta, "content"):
+                            replies_dict[choice.index] += choice.delta.content
+                        metadata_dict[choice.index] = {
+                            "model": chunk.model,
+                            "index": choice.index,
+                            "finish_reason": choice.finish_reason,
+                        }
+                all_replies.append(list(replies_dict.values()))
+                all_metadata.append(list(metadata_dict.values()))
+                self._check_truncated_answers(list(metadata_dict.values()))
+
+            else:
+                metadata = [
+                    {
+                        "model": completion.model,
+                        "index": choice.index,
+                        "finish_reason": choice.finish_reason,
+                        "usage": dict(completion.usage.items()),
+                    }
+                    for choice in completion.choices
+                ]
+                replies = [choice.message.content.strip() for choice in completion.choices]
+                all_replies.append(replies)
+                all_metadata.append(metadata)
+                self._check_truncated_answers(metadata)
+
+        return {"replies": all_replies, "metadata": all_metadata}
+
+    def _check_truncated_answers(self, metadata: List[Dict[str, Any]]):
+        """
+        Check the `finish_reason` returned with the OpenAI completions.
+        If the `finish_reason` is `length`, log a warning to the user.
+
+        :param result: The result returned from the OpenAI API.
+        :param payload: The payload sent to the OpenAI API.
+        """
+        truncated_completions = sum(1 for meta in metadata if meta.get("finish_reason") != "stop")
+        if truncated_completions > 0:
+            logger.warning(
+                "%s out of the %s completions have been truncated before reaching a natural stopping point. "
+                "Increase the max_tokens parameter to allow for longer completions.",
+                truncated_completions,
+                len(metadata),
+            )
diff --git a/pyproject.toml b/pyproject.toml
index cd3f2068a3..1b2a577eba 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -80,6 +80,7 @@ dependencies = [
 
   # Preview
   "canals==0.8.0",
+  "openai",
   "Jinja2",
   "openai-whisper",  # FIXME https://github.com/deepset-ai/haystack/issues/5731
 
diff --git a/releasenotes/notes/chatgpt-llm-generator-d043532654efe684.yaml b/releasenotes/notes/chatgpt-llm-generator-d043532654efe684.yaml
new file mode 100644
index 0000000000..13d9491a1e
--- /dev/null
+++ b/releasenotes/notes/chatgpt-llm-generator-d043532654efe684.yaml
@@ -0,0 +1,2 @@
+preview:
+  - Introduce `GPT35Generator`, a class that can generate completions using OpenAI Chat models like GPT3.5 and GPT4.
diff --git a/test/preview/components/generators/openai/test_gpt35_generator.py b/test/preview/components/generators/openai/test_gpt35_generator.py
new file mode 100644
index 0000000000..c4bc9c512f
--- /dev/null
+++ b/test/preview/components/generators/openai/test_gpt35_generator.py
@@ -0,0 +1,332 @@
+from unittest.mock import patch, Mock
+from copy import deepcopy
+
+import pytest
+import openai
+from openai.util import convert_to_openai_object
+
+from haystack.preview.components.generators.openai.gpt35 import GPT35Generator
+from haystack.preview.components.generators.openai.gpt35 import default_streaming_callback
+
+
+def mock_openai_response(messages: str, model: str = "gpt-3.5-turbo-0301", **kwargs) -> openai.ChatCompletion:
+    response = f"response for these messages --> {' - '.join(msg['role']+': '+msg['content'] for msg in messages)}"
+    base_dict = {
+        "id": "chatcmpl-7NaPEA6sgX7LnNPyKPbRlsyqLbr5V",
+        "object": "chat.completion",
+        "created": 1685855844,
+        "model": model,
+        "usage": {"prompt_tokens": 57, "completion_tokens": 40, "total_tokens": 97},
+    }
+    base_dict["choices"] = [
+        {"message": {"role": "assistant", "content": response}, "finish_reason": "stop", "index": "0"}
+    ]
+    return convert_to_openai_object(deepcopy(base_dict))
+
+
+def mock_openai_stream_response(messages: str, model: str = "gpt-3.5-turbo-0301", **kwargs) -> openai.ChatCompletion:
+    response = f"response for these messages --> {' - '.join(msg['role']+': '+msg['content'] for msg in messages)}"
+    base_dict = {
+        "id": "chatcmpl-7NaPEA6sgX7LnNPyKPbRlsyqLbr5V",
+        "object": "chat.completion",
+        "created": 1685855844,
+        "model": model,
+    }
+    base_dict["choices"] = [{"delta": {"role": "assistant"}, "finish_reason": None, "index": "0"}]
+    yield convert_to_openai_object(base_dict)
+    for token in response.split():
+        base_dict["choices"][0]["delta"] = {"content": token + " "}
+        yield convert_to_openai_object(base_dict)
+    base_dict["choices"] = [{"delta": {"content": ""}, "finish_reason": "stop", "index": "0"}]
+    yield convert_to_openai_object(base_dict)
+
+
+class TestGPT35Generator:
+    @pytest.mark.unit
+    def test_init_default(self):
+        component = GPT35Generator(api_key="test-api-key")
+        assert component.system_prompt is None
+        assert component.api_key == "test-api-key"
+        assert component.model_name == "gpt-3.5-turbo"
+        assert component.streaming_callback is None
+        assert component.api_base_url == "https://api.openai.com/v1"
+        assert component.model_parameters == {}
+
+    @pytest.mark.unit
+    def test_init_with_parameters(self):
+        callback = lambda x: x
+        component = GPT35Generator(
+            api_key="test-api-key",
+            model_name="gpt-4",
+            system_prompt="test-system-prompt",
+            max_tokens=10,
+            some_test_param="test-params",
+            streaming_callback=callback,
+            api_base_url="test-base-url",
+        )
+        assert component.system_prompt == "test-system-prompt"
+        assert component.api_key == "test-api-key"
+        assert component.model_name == "gpt-4"
+        assert component.streaming_callback == callback
+        assert component.api_base_url == "test-base-url"
+        assert component.model_parameters == {"max_tokens": 10, "some_test_param": "test-params"}
+
+    @pytest.mark.unit
+    def test_to_dict_default(self):
+        component = GPT35Generator(api_key="test-api-key")
+        data = component.to_dict()
+        assert data == {
+            "type": "GPT35Generator",
+            "init_parameters": {
+                "api_key": "test-api-key",
+                "model_name": "gpt-3.5-turbo",
+                "system_prompt": None,
+                "streaming_callback": None,
+                "api_base_url": "https://api.openai.com/v1",
+            },
+        }
+
+    @pytest.mark.unit
+    def test_to_dict_with_parameters(self):
+        component = GPT35Generator(
+            api_key="test-api-key",
+            model_name="gpt-4",
+            system_prompt="test-system-prompt",
+            max_tokens=10,
+            some_test_param="test-params",
+            streaming_callback=default_streaming_callback,
+            api_base_url="test-base-url",
+        )
+        data = component.to_dict()
+        assert data == {
+            "type": "GPT35Generator",
+            "init_parameters": {
+                "api_key": "test-api-key",
+                "model_name": "gpt-4",
+                "system_prompt": "test-system-prompt",
+                "max_tokens": 10,
+                "some_test_param": "test-params",
+                "api_base_url": "test-base-url",
+                "streaming_callback": "haystack.preview.components.generators.openai.gpt35.default_streaming_callback",
+            },
+        }
+
+    @pytest.mark.unit
+    def test_to_dict_with_lambda_streaming_callback(self):
+        component = GPT35Generator(
+            api_key="test-api-key",
+            model_name="gpt-4",
+            system_prompt="test-system-prompt",
+            max_tokens=10,
+            some_test_param="test-params",
+            streaming_callback=lambda x: x,
+            api_base_url="test-base-url",
+        )
+        data = component.to_dict()
+        assert data == {
+            "type": "GPT35Generator",
+            "init_parameters": {
+                "api_key": "test-api-key",
+                "model_name": "gpt-4",
+                "system_prompt": "test-system-prompt",
+                "max_tokens": 10,
+                "some_test_param": "test-params",
+                "api_base_url": "test-base-url",
+                "streaming_callback": "test_gpt35_generator.<lambda>",
+            },
+        }
+
+    @pytest.mark.unit
+    def test_from_dict(self):
+        data = {
+            "type": "GPT35Generator",
+            "init_parameters": {
+                "api_key": "test-api-key",
+                "model_name": "gpt-4",
+                "system_prompt": "test-system-prompt",
+                "max_tokens": 10,
+                "some_test_param": "test-params",
+                "api_base_url": "test-base-url",
+                "streaming_callback": "haystack.preview.components.generators.openai.gpt35.default_streaming_callback",
+            },
+        }
+        component = GPT35Generator.from_dict(data)
+        assert component.system_prompt == "test-system-prompt"
+        assert component.api_key == "test-api-key"
+        assert component.model_name == "gpt-4"
+        assert component.streaming_callback == default_streaming_callback
+        assert component.api_base_url == "test-base-url"
+        assert component.model_parameters == {"max_tokens": 10, "some_test_param": "test-params"}
+
+    @pytest.mark.unit
+    def test_run_no_system_prompt(self):
+        with patch("haystack.preview.components.generators.openai.gpt35.openai.ChatCompletion") as gpt35_patch:
+            gpt35_patch.create.side_effect = mock_openai_response
+            component = GPT35Generator(api_key="test-api-key")
+            results = component.run(prompts=["test-prompt-1", "test-prompt-2"])
+            assert results == {
+                "replies": [
+                    ["response for these messages --> user: test-prompt-1"],
+                    ["response for these messages --> user: test-prompt-2"],
+                ],
+                "metadata": [
+                    [
+                        {
+                            "model": "gpt-3.5-turbo",
+                            "index": "0",
+                            "finish_reason": "stop",
+                            "usage": {"prompt_tokens": 57, "completion_tokens": 40, "total_tokens": 97},
+                        }
+                    ],
+                    [
+                        {
+                            "model": "gpt-3.5-turbo",
+                            "index": "0",
+                            "finish_reason": "stop",
+                            "usage": {"prompt_tokens": 57, "completion_tokens": 40, "total_tokens": 97},
+                        }
+                    ],
+                ],
+            }
+            assert gpt35_patch.create.call_count == 2
+            gpt35_patch.create.assert_any_call(
+                model="gpt-3.5-turbo",
+                api_key="test-api-key",
+                messages=[{"role": "user", "content": "test-prompt-1"}],
+                stream=False,
+            )
+            gpt35_patch.create.assert_any_call(
+                model="gpt-3.5-turbo",
+                api_key="test-api-key",
+                messages=[{"role": "user", "content": "test-prompt-2"}],
+                stream=False,
+            )
+
+    @pytest.mark.unit
+    def test_run_with_system_prompt(self):
+        with patch("haystack.preview.components.generators.openai.gpt35.openai.ChatCompletion") as gpt35_patch:
+            gpt35_patch.create.side_effect = mock_openai_response
+            component = GPT35Generator(api_key="test-api-key", system_prompt="test-system-prompt")
+            results = component.run(prompts=["test-prompt-1", "test-prompt-2"])
+            assert results == {
+                "replies": [
+                    ["response for these messages --> system: test-system-prompt - user: test-prompt-1"],
+                    ["response for these messages --> system: test-system-prompt - user: test-prompt-2"],
+                ],
+                "metadata": [
+                    [
+                        {
+                            "model": "gpt-3.5-turbo",
+                            "index": "0",
+                            "finish_reason": "stop",
+                            "usage": {"prompt_tokens": 57, "completion_tokens": 40, "total_tokens": 97},
+                        }
+                    ],
+                    [
+                        {
+                            "model": "gpt-3.5-turbo",
+                            "index": "0",
+                            "finish_reason": "stop",
+                            "usage": {"prompt_tokens": 57, "completion_tokens": 40, "total_tokens": 97},
+                        }
+                    ],
+                ],
+            }
+            assert gpt35_patch.create.call_count == 2
+            gpt35_patch.create.assert_any_call(
+                model="gpt-3.5-turbo",
+                api_key="test-api-key",
+                messages=[
+                    {"role": "system", "content": "test-system-prompt"},
+                    {"role": "user", "content": "test-prompt-1"},
+                ],
+                stream=False,
+            )
+            gpt35_patch.create.assert_any_call(
+                model="gpt-3.5-turbo",
+                api_key="test-api-key",
+                messages=[
+                    {"role": "system", "content": "test-system-prompt"},
+                    {"role": "user", "content": "test-prompt-2"},
+                ],
+                stream=False,
+            )
+
+    @pytest.mark.unit
+    def test_run_with_parameters(self):
+        with patch("haystack.preview.components.generators.openai.gpt35.openai.ChatCompletion") as gpt35_patch:
+            gpt35_patch.create.side_effect = mock_openai_response
+            component = GPT35Generator(api_key="test-api-key", max_tokens=10)
+            component.run(prompts=["test-prompt-1", "test-prompt-2"])
+            assert gpt35_patch.create.call_count == 2
+            gpt35_patch.create.assert_any_call(
+                model="gpt-3.5-turbo",
+                api_key="test-api-key",
+                messages=[{"role": "user", "content": "test-prompt-1"}],
+                stream=False,
+                max_tokens=10,
+            )
+            gpt35_patch.create.assert_any_call(
+                model="gpt-3.5-turbo",
+                api_key="test-api-key",
+                messages=[{"role": "user", "content": "test-prompt-2"}],
+                stream=False,
+                max_tokens=10,
+            )
+
+    @pytest.mark.unit
+    def test_run_stream(self):
+        with patch("haystack.preview.components.generators.openai.gpt35.openai.ChatCompletion") as gpt35_patch:
+            mock_callback = Mock()
+            mock_callback.side_effect = default_streaming_callback
+            gpt35_patch.create.side_effect = mock_openai_stream_response
+            component = GPT35Generator(
+                api_key="test-api-key", system_prompt="test-system-prompt", streaming_callback=mock_callback
+            )
+            results = component.run(prompts=["test-prompt-1", "test-prompt-2"])
+            assert results == {
+                "replies": [
+                    ["response for these messages --> system: test-system-prompt - user: test-prompt-1 "],
+                    ["response for these messages --> system: test-system-prompt - user: test-prompt-2 "],
+                ],
+                "metadata": [
+                    [{"model": "gpt-3.5-turbo", "index": "0", "finish_reason": "stop"}],
+                    [{"model": "gpt-3.5-turbo", "index": "0", "finish_reason": "stop"}],
+                ],
+            }
+            # Calls count: (10 tokens per prompt + 1 token for the role + 1 empty termination token) * 2 prompts
+            assert mock_callback.call_count == 24
+            assert gpt35_patch.create.call_count == 2
+            gpt35_patch.create.assert_any_call(
+                model="gpt-3.5-turbo",
+                api_key="test-api-key",
+                messages=[
+                    {"role": "system", "content": "test-system-prompt"},
+                    {"role": "user", "content": "test-prompt-1"},
+                ],
+                stream=True,
+            )
+            gpt35_patch.create.assert_any_call(
+                model="gpt-3.5-turbo",
+                api_key="test-api-key",
+                messages=[
+                    {"role": "system", "content": "test-system-prompt"},
+                    {"role": "user", "content": "test-prompt-2"},
+                ],
+                stream=True,
+            )
+
+    @pytest.mark.unit
+    def test_check_truncated_answers(self, caplog):
+        component = GPT35Generator(api_key="test-api-key")
+        metadata = [
+            {"finish_reason": "stop"},
+            {"finish_reason": "content_filter"},
+            {"finish_reason": "length"},
+            {"finish_reason": "stop"},
+        ]
+        component._check_truncated_answers(metadata)
+        assert caplog.records[0].message == (
+            "2 out of the 4 completions have been truncated before reaching a natural "
+            "stopping point. Increase the max_tokens parameter to allow for longer completions."
+        )
diff --git a/test/preview/components/generators/openai/test_openai_helpers.py b/test/preview/components/generators/openai/test_openai_helpers.py
deleted file mode 100644
index 23a66117d1..0000000000
--- a/test/preview/components/generators/openai/test_openai_helpers.py
+++ /dev/null
@@ -1,20 +0,0 @@
-import pytest
-
-from haystack.preview.components.generators.openai._helpers import enforce_token_limit
-
-
-@pytest.mark.unit
-def test_enforce_token_limit_above_limit(caplog, mock_tokenizer):
-    prompt = enforce_token_limit("This is a test prompt.", tokenizer=mock_tokenizer, max_tokens_limit=3)
-    assert prompt == "This is a"
-    assert caplog.records[0].message == (
-        "The prompt has been truncated from 5 tokens to 3 tokens to fit within the max token "
-        "limit. Reduce the length of the prompt to prevent it from being cut off."
-    )
-
-
-@pytest.mark.unit
-def test_enforce_token_limit_below_limit(caplog, mock_tokenizer):
-    prompt = enforce_token_limit("This is a test prompt.", tokenizer=mock_tokenizer, max_tokens_limit=100)
-    assert prompt == "This is a test prompt."
-    assert not caplog.records
diff --git a/test/preview/conftest.py b/test/preview/conftest.py
index b8abfa41a6..d8882ea230 100644
--- a/test/preview/conftest.py
+++ b/test/preview/conftest.py
@@ -1,4 +1,4 @@
-from unittest.mock import Mock
+from unittest.mock import Mock, patch
 import pytest