diff --git a/langfuse/langchain/utils.py b/langfuse/langchain/utils.py
index 544bcf957..d39562f79 100644
--- a/langfuse/langchain/utils.py
+++ b/langfuse/langchain/utils.py
@@ -70,8 +70,12 @@ def _extract_model_name(
 
             serialized_kwargs = serialized.get("kwargs")
             if serialized_kwargs and isinstance(serialized_kwargs, dict):
+                # LangChain's AzureOpenAI exposes the API version under
+                # `openai_api_version`, not `deployment_version` — the latter
+                # is never populated, so previously the version suffix was
+                # dropped from the resulting model name.
                 if serialized_kwargs.get("openai_api_version"):
-                    deployment_version = serialized_kwargs.get("deployment_version")
+                    deployment_version = serialized_kwargs.get("openai_api_version")
 
                 if serialized_kwargs.get("deployment_name"):
                     deployment_name = serialized_kwargs.get("deployment_name")
diff --git a/tests/unit/test_extract_model_name.py b/tests/unit/test_extract_model_name.py
new file mode 100644
index 000000000..4f9f0869e
--- /dev/null
+++ b/tests/unit/test_extract_model_name.py
@@ -0,0 +1,47 @@
+"""Unit tests for ``langfuse.langchain.utils._extract_model_name``."""
+
+from langfuse.langchain.utils import _extract_model_name
+
+
+def _azure_openai_serialized(
+    *, deployment_name: str, openai_api_version: str | None
+) -> dict:
+    """Build a minimal ``serialized`` dict mirroring what LangChain emits for AzureOpenAI."""
+    kwargs: dict = {"deployment_name": deployment_name}
+    if openai_api_version is not None:
+        kwargs["openai_api_version"] = openai_api_version
+    return {"id": ["langchain", "llms", "openai", "AzureOpenAI"], "kwargs": kwargs}
+
+
+def test_azure_openai_returns_deployment_name_with_api_version_suffix():
+    """Regression: ``openai_api_version`` should be appended to the deployment name.
+
+    Previously the code read the value from a non-existent ``deployment_version``
+    key after checking that ``openai_api_version`` was set, so the suffix was
+    silently dropped.
+    """
+    serialized = _azure_openai_serialized(
+        deployment_name="my-deployment",
+        openai_api_version="2024-02-15-preview",
+    )
+    assert _extract_model_name(serialized) == "my-deployment-2024-02-15-preview"
+
+
+def test_azure_openai_returns_bare_deployment_name_when_no_api_version():
+    serialized = _azure_openai_serialized(
+        deployment_name="my-deployment",
+        openai_api_version=None,
+    )
+    assert _extract_model_name(serialized) == "my-deployment"
+
+
+def test_azure_openai_no_duplicate_version_suffix():
+    """If the deployment_name already contains the version, don't append it again.
+
+    This guards the existing behavior introduced in PR #1203.
+    """
+    serialized = _azure_openai_serialized(
+        deployment_name="my-deployment-2024-02-15-preview",
+        openai_api_version="2024-02-15-preview",
+    )
+    assert _extract_model_name(serialized) == "my-deployment-2024-02-15-preview"