diff --git a/UPDATING.md b/UPDATING.md
index 7da20adb306ac2..cb27425b148946 100644
--- a/UPDATING.md
+++ b/UPDATING.md
@@ -106,6 +106,14 @@ delete this option.
 The TriggerDagRunOperator now takes a `conf` argument to which a dict can be provided as conf for the DagRun.
 As a result, the `python_callable` argument was removed. PR: https://github.com/apache/airflow/pull/6317.
 
+### Changes in experimental API execution_date microseconds replacement
+
+The default behavior was to strip the microseconds (and milliseconds, etc) off of all dag runs triggered by
+by the experimental REST API.  The default behavior will change when an explicit execution_date is
+passed in the request body.  It will also now be possible to have the execution_date generated, but
+keep the microseconds by sending `replace_microseconds=false` in the request body.  The default
+behavior can be overridden by sending `replace_microseconds=true` along with an explicit execution_date
+
 ### Changes in Google Cloud Platform related hooks
 
 The change in GCP operators implies that GCP Hooks for those operators require now keyword parameters rather
diff --git a/airflow/utils/strings.py b/airflow/utils/strings.py
index 63c44b821259bc..d8a52ff47809e5 100644
--- a/airflow/utils/strings.py
+++ b/airflow/utils/strings.py
@@ -28,3 +28,10 @@ def get_random_string(length=8, choices=string.ascii_letters + string.digits):
     Generate random string
     '''
     return ''.join([choice(choices) for _ in range(length)])
+
+
+def to_boolean(astring):
+    '''
+    Convert a string to a boolean
+    '''
+    return astring.lower() in ['true', 't', 'y', 'yes', '1']
diff --git a/airflow/www/api/experimental/endpoints.py b/airflow/www/api/experimental/endpoints.py
index 1aa0662abfacac..67204f72d2c344 100644
--- a/airflow/www/api/experimental/endpoints.py
+++ b/airflow/www/api/experimental/endpoints.py
@@ -29,6 +29,7 @@
 from airflow.exceptions import AirflowException
 from airflow.utils import timezone
 from airflow.utils.log.logging_mixin import LoggingMixin
+from airflow.utils.strings import to_boolean
 from airflow.www.app import csrf
 
 _log = LoggingMixin().log
@@ -74,8 +75,12 @@ def trigger_dag(dag_id):
 
             return response
 
+    replace_microseconds = (execution_date is None)
+    if 'replace_microseconds' in data:
+        replace_microseconds = to_boolean(data['replace_microseconds'])
+
     try:
-        dr = trigger.trigger_dag(dag_id, run_id, conf, execution_date)
+        dr = trigger.trigger_dag(dag_id, run_id, conf, execution_date, replace_microseconds)
     except AirflowException as err:
         _log.error(err)
         response = jsonify(error="{}".format(err))
diff --git a/tests/www/api/experimental/test_endpoints.py b/tests/www/api/experimental/test_endpoints.py
index 8a6da70131e3e8..e2de9974529075 100644
--- a/tests/www/api/experimental/test_endpoints.py
+++ b/tests/www/api/experimental/test_endpoints.py
@@ -129,13 +129,17 @@ def test_trigger_dag(self):
         )
 
         self.assertEqual(200, response.status_code)
+        response_execution_date = parse_datetime(json.loads(response.data.decode('utf-8'))['execution_date'])
+        self.assertEqual(0, response_execution_date.microsecond)
+
         # Check execution_date is correct
         response = json.loads(response.data.decode('utf-8'))
         dagbag = DagBag()
         dag = dagbag.get_dag('example_bash_operator')
-        dag_run = dag.get_dagrun(parse_datetime(response['execution_date']))
+        dag_run = dag.get_dagrun(response_execution_date)
         self.assertEqual(run_id, dag_run.run_id)
 
+        # Test error for nonexistent dag
         response = self.client.post(
             url_template.format('does_not_exist_dag'),
             data=json.dumps({}),
@@ -146,14 +150,10 @@ def test_trigger_dag(self):
     def test_trigger_dag_for_date(self):
         url_template = '/api/experimental/dags/{}/dag_runs'
         dag_id = 'example_bash_operator'
-        hour_from_now = utcnow() + timedelta(hours=1)
-        execution_date = datetime(hour_from_now.year,
-                                  hour_from_now.month,
-                                  hour_from_now.day,
-                                  hour_from_now.hour)
+        execution_date = utcnow() + timedelta(hours=1)
         datetime_string = execution_date.isoformat()
 
-        # Test Correct execution
+        # Test correct execution with execution date
         response = self.client.post(
             url_template.format(dag_id),
             data=json.dumps({'execution_date': datetime_string}),
@@ -169,10 +169,27 @@ def test_trigger_dag_for_date(self):
                         'Dag Run not found for execution date {}'
                         .format(execution_date))
 
+        # Test correct execution with execution date and microseconds replaced
+        response = self.client.post(
+            url_template.format(dag_id),
+            data=json.dumps({'execution_date': datetime_string, 'replace_microseconds': 'true'}),
+            content_type="application/json"
+        )
+        self.assertEqual(200, response.status_code)
+        response_execution_date = parse_datetime(json.loads(response.data.decode('utf-8'))['execution_date'])
+        self.assertEqual(0, response_execution_date.microsecond)
+
+        dagbag = DagBag()
+        dag = dagbag.get_dag(dag_id)
+        dag_run = dag.get_dagrun(response_execution_date)
+        self.assertTrue(dag_run,
+                        'Dag Run not found for execution date {}'
+                        .format(execution_date))
+
         # Test error for nonexistent dag
         response = self.client.post(
             url_template.format('does_not_exist_dag'),
-            data=json.dumps({'execution_date': execution_date.isoformat()}),
+            data=json.dumps({'execution_date': datetime_string}),
             content_type="application/json"
         )
         self.assertEqual(404, response.status_code)