diff --git a/moto/stepfunctions/models.py b/moto/stepfunctions/models.py
index 6217a6bc7..fedcb8e77 100644
--- a/moto/stepfunctions/models.py
+++ b/moto/stepfunctions/models.py
@@ -96,12 +96,12 @@ class StepFunctionBackend(BaseBackend):
         if sm:
             self.state_machines.remove(sm)
 
-    def start_execution(self, state_machine_arn):
+    def start_execution(self, state_machine_arn, name=None):
         state_machine_name = self.describe_state_machine(state_machine_arn).name
         execution = Execution(region_name=self.region_name,
                               account_id=self._get_account_id(),
                               state_machine_name=state_machine_name,
-                              execution_name=str(uuid4()),
+                              execution_name=name or str(uuid4()),
                               state_machine_arn=state_machine_arn)
         self.executions.append(execution)
         return execution
diff --git a/moto/stepfunctions/responses.py b/moto/stepfunctions/responses.py
index 0a170aa57..902a860e5 100644
--- a/moto/stepfunctions/responses.py
+++ b/moto/stepfunctions/responses.py
@@ -86,7 +86,8 @@ class StepFunctionResponse(BaseResponse):
     @amzn_request_id
     def start_execution(self):
         arn = self._get_param('stateMachineArn')
-        execution = self.stepfunction_backend.start_execution(arn)
+        name = self._get_param('name')
+        execution = self.stepfunction_backend.start_execution(arn, name)
         response = {'executionArn': execution.execution_arn,
                     'startDate': execution.start_date}
         return 200, {}, json.dumps(response)
diff --git a/tests/test_stepfunctions/test_stepfunctions.py b/tests/test_stepfunctions/test_stepfunctions.py
index 6c7fd8e26..6c1e7e4c8 100644
--- a/tests/test_stepfunctions/test_stepfunctions.py
+++ b/tests/test_stepfunctions/test_stepfunctions.py
@@ -243,11 +243,26 @@ def test_state_machine_start_execution():
     execution = client.start_execution(stateMachineArn=sm['stateMachineArn'])
     #
     execution['ResponseMetadata']['HTTPStatusCode'].should.equal(200)
-    expected_exec_name = 'arn:aws:states:' + region + ':' + _get_account_id() + ':execution:name:[a-zA-Z0-9-]+'
+    uuid_regex = '[a-f0-9]{8}-[a-f0-9]{4}-[a-f0-9]{4}-[a-f0-9]{4}-[a-f0-9]{12}'
+    expected_exec_name = 'arn:aws:states:' + region + ':' + _get_account_id() + ':execution:name:' + uuid_regex
     execution['executionArn'].should.match(expected_exec_name)
     execution['startDate'].should.be.a(datetime)
 
 
+@mock_stepfunctions
+@mock_sts
+def test_state_machine_start_execution_with_custom_name():
+    client = boto3.client('stepfunctions', region_name=region)
+    #
+    sm = client.create_state_machine(name='name', definition=str(simple_definition), roleArn=_get_default_role())
+    execution = client.start_execution(stateMachineArn=sm['stateMachineArn'], name='execution_name')
+    #
+    execution['ResponseMetadata']['HTTPStatusCode'].should.equal(200)
+    expected_exec_name = 'arn:aws:states:' + region + ':' + _get_account_id() + ':execution:name:execution_name'
+    execution['executionArn'].should.equal(expected_exec_name)
+    execution['startDate'].should.be.a(datetime)
+
+
 @mock_stepfunctions
 @mock_sts
 def test_state_machine_list_executions():