diff --git a/autogen/oai/gemini.py b/autogen/oai/gemini.py
index 54a5c85d3fe..30d4c3fe518 100644
--- a/autogen/oai/gemini.py
+++ b/autogen/oai/gemini.py
@@ -194,7 +194,7 @@ def create(self, params: Dict) -> ChatCompletion:
             for attempt in range(max_retries):
                 ans = None
                 try:
-                    response = chat.send_message(gemini_messages[-1].parts[0].text, stream=stream)
+                    response = chat.send_message(gemini_messages[-1], stream=stream)
                 except InternalServerError:
                     delay = 5 * (2**attempt)
                     warnings.warn(
@@ -344,19 +344,19 @@ def _oai_messages_to_gemini_messages(self, messages: list[Dict[str, Any]]) -> li
         for i, message in enumerate(messages):
             parts = self._oai_content_to_gemini_content(message["content"])
             role = "user" if message["role"] in ["user", "system"] else "model"
-
-            if prev_role is None or role == prev_role:
+            if (prev_role is None) or (role == prev_role):
                 curr_parts += parts
             elif role != prev_role:
                 if self.use_vertexai:
-                    rst.append(VertexAIContent(parts=self._concat_parts(curr_parts), role=prev_role))
+                    rst.append(VertexAIContent(parts=curr_parts, role=prev_role))
                 else:
                     rst.append(Content(parts=curr_parts, role=prev_role))
+                curr_parts = parts
             prev_role = role
 
         # handle the last message
         if self.use_vertexai:
-            rst.append(VertexAIContent(parts=self._concat_parts(curr_parts), role=role))
+            rst.append(VertexAIContent(parts=curr_parts, role=role))
         else:
             rst.append(Content(parts=curr_parts, role=role))
 
diff --git a/test/oai/test_gemini.py b/test/oai/test_gemini.py
index 4f77d288789..35f35620b8b 100644
--- a/test/oai/test_gemini.py
+++ b/test/oai/test_gemini.py
@@ -52,6 +52,48 @@ def test_valid_initialization(gemini_client):
     assert gemini_client.api_key == "fake_api_key", "API Key should be correctly set"
 
 
+@pytest.mark.skipif(skip, reason="Google GenAI dependency is not installed")
+def test_gemini_message_handling(gemini_client):
+    messages = [
+        {"role": "system", "content": "You are my personal assistant."},
+        {"role": "model", "content": "How can I help you?"},
+        {"role": "user", "content": "Which planet is the nearest to the sun?"},
+        {"role": "user", "content": "Which planet is the farthest from the sun?"},
+        {"role": "model", "content": "Mercury is the closest palnet to the sun."},
+        {"role": "model", "content": "Neptune is the farthest palnet from the sun."},
+        {"role": "user", "content": "How can we determine the mass of a black hole?"},
+    ]
+
+    # The datastructure below defines what the structure of the messages
+    # should resemble after converting to Gemini format.
+    # Messages of similar roles are expected to be merged to a single message,
+    # where the contents of the original messages will be included in
+    # consecutive parts of the converted Gemini message
+    expected_gemini_struct = [
+        # system role is converted to user role
+        {"role": "user", "parts": ["You are my personal assistant."]},
+        {"role": "model", "parts": ["How can I help you?"]},
+        {
+            "role": "user",
+            "parts": ["Which planet is the nearest to the sun?", "Which planet is the farthest from the sun?"],
+        },
+        {
+            "role": "model",
+            "parts": ["Mercury is the closest palnet to the sun.", "Neptune is the farthest palnet from the sun."],
+        },
+        {"role": "user", "parts": ["How can we determine the mass of a black hole?"]},
+    ]
+
+    converted_messages = gemini_client._oai_messages_to_gemini_messages(messages)
+
+    assert len(converted_messages) == len(expected_gemini_struct), "The number of messages is not as expected"
+
+    for i, expected_msg in enumerate(expected_gemini_struct):
+        assert expected_msg["role"] == converted_messages[i].role, "Incorrect mapped message role"
+        for j, part in enumerate(expected_msg["parts"]):
+            assert converted_messages[i].parts[j].text == part, "Incorrect mapped message text"
+
+
 # Test error handling
 @patch("autogen.oai.gemini.genai")
 @pytest.mark.skipif(skip, reason="Google GenAI dependency is not installed")