diff --git a/.changeset/support_non_standard_http_codes.md b/.changeset/support_non_standard_http_codes.md
@@ -0,0 +1,15 @@
+---
+default: minor
+---
+
+# Summary
+
+Added support for responses with non-standard HTTP Status Codes. Off by default, enabled with `allow_int_response_codes`.
+
+# Problem
+
+Currently if a response with a status code that does not exist in `http.HTTPStatusCode` a `ValueError` is raised. For example: `ValueError: 490 is not a valid HTTPStatus`.
+
+# Edge Case
+
+If a non-standard status code is received from an endpoint that doesn't define any responses with non-standard status codes the old behavior will appear.
diff --git a/end_to_end_tests/baseline_openapi_3.0.json b/end_to_end_tests/baseline_openapi_3.0.json
@@ -1736,6 +1736,27 @@
         }
       }
     },
+    "/tests/nonstandard-response-code": {
+      "get": {
+        "tags": [
+          "tests"
+        ],
+        "summary": "Test nonstandard response code",
+        "description": "Test endpoint with nonstandard response code",
+        "operationId": "nonstandard_response_code",
+        "responses": {
+          "200": {
+            "description": "Successful response"
+          },
+          "499": {
+            "description": "Nonstandard response code"
+          },
+          "99999": {
+            "description": "Nonstandard response code"
+          }
+        }
+      }
+    },
     "/config/content-type-override": {
       "post": {
         "tags": [

diff --git a/end_to_end_tests/baseline_openapi_3.1.yaml b/end_to_end_tests/baseline_openapi_3.1.yaml
@@ -1706,6 +1706,27 @@ info:
       }
     }
   },
+  "/tests/nonstandard-response-code": {
+      "get": {
+        "tags": [
+          "tests"
+        ],
+        "summary": "Test nonstandard response code",
+        "description": "Test endpoint with nonstandard response code",
+        "operationId": "nonstandard_response_code",
+        "responses": {
+          "200": {
+            "description": "Successful response"
+          },
+          "499": {
+            "description": "Nonstandard response code"
+          },
+          "99999": {
+            "description": "Nonstandard response code"
+          }
+        }
+      }
+    },
   "/config/content-type-override": {
     "post": {
       "tags": [

diff --git a/end_to_end_tests/config.yml b/end_to_end_tests/config.yml
@@ -12,3 +12,4 @@ field_prefix: attr_
 content_type_overrides:
    openapi/python/client: application/json
 generate_all_tags: true
+allow_int_response_codes: true
diff --git a/end_to_end_tests/custom-templates-golden-record/my_test_api_client/api/tests/__init__.py b/end_to_end_tests/custom-templates-golden-record/my_test_api_client/api/tests/__init__.py
@@ -12,6 +12,7 @@
     get_user_list,
     json_body_tests_json_body_post,
     no_response_tests_no_response_get,
+    nonstandard_response_code,
     octet_stream_tests_octet_stream_get,
     octet_stream_tests_octet_stream_post,
     post_form_data,
@@ -150,3 +151,10 @@ def description_with_backslash(cls) -> types.ModuleType:
             Test description with \
         """
         return description_with_backslash
+
+    @classmethod
+    def nonstandard_response_code(cls) -> types.ModuleType:
+        """
+        Test endpoint with nonstandard response code
+        """
+        return nonstandard_response_code
diff --git a/end_to_end_tests/docstrings-on-attributes-golden-record/my_test_api_client/types.py b/end_to_end_tests/docstrings-on-attributes-golden-record/my_test_api_client/types.py
@@ -39,13 +39,14 @@ def to_tuple(self) -> FileTypes:
 
 
 T = TypeVar("T")
+S = TypeVar("S", bound=HTTPStatus | int)
 
 
 @define
-class Response(Generic[T]):
+class Response(Generic[T, S]):
     """A response from an endpoint"""
 
-    status_code: HTTPStatus
+    status_code: S
     content: bytes
     headers: MutableMapping[str, str]
     parsed: T | None

diff --git a/end_to_end_tests/golden-record/my_test_api_client/api/bodies/json_like.py b/end_to_end_tests/golden-record/my_test_api_client/api/bodies/json_like.py
@@ -1,4 +1,4 @@
-from http import HTTPStatus
+import http
 from typing import Any
 
 import httpx
@@ -39,9 +39,11 @@ def _parse_response(*, client: AuthenticatedClient | Client, response: httpx.Res
         return None
 
 
-def _build_response(*, client: AuthenticatedClient | Client, response: httpx.Response) -> Response[Any]:
+def _build_response(
+    *, client: AuthenticatedClient | Client, response: httpx.Response
+) -> Response[Any, http.HTTPStatus]:
     return Response(
-        status_code=HTTPStatus(response.status_code),
+        status_code=http.HTTPStatus(response.status_code),
         content=response.content,
         headers=response.headers,
         parsed=_parse_response(client=client, response=response),
@@ -52,7 +54,7 @@ def sync_detailed(
     *,
     client: AuthenticatedClient | Client,
     body: JsonLikeBody | Unset = UNSET,
-) -> Response[Any]:
+) -> Response[Any, http.HTTPStatus]:
     """A content type that works like json but isn't application/json
 
     Args:
@@ -81,7 +83,7 @@ async def asyncio_detailed(
     *,
     client: AuthenticatedClient | Client,
     body: JsonLikeBody | Unset = UNSET,
-) -> Response[Any]:
+) -> Response[Any, http.HTTPStatus]:
     """A content type that works like json but isn't application/json
 
     Args:

diff --git a/end_to_end_tests/golden-record/my_test_api_client/api/bodies/optional_body.py b/end_to_end_tests/golden-record/my_test_api_client/api/bodies/optional_body.py
@@ -1,4 +1,4 @@
-from http import HTTPStatus
+import http
 from typing import Any
 
 import httpx
@@ -39,9 +39,11 @@ def _parse_response(*, client: AuthenticatedClient | Client, response: httpx.Res
         return None
 
 
-def _build_response(*, client: AuthenticatedClient | Client, response: httpx.Response) -> Response[Any]:
+def _build_response(
+    *, client: AuthenticatedClient | Client, response: httpx.Response
+) -> Response[Any, http.HTTPStatus]:
     return Response(
-        status_code=HTTPStatus(response.status_code),
+        status_code=http.HTTPStatus(response.status_code),
         content=response.content,
         headers=response.headers,
         parsed=_parse_response(client=client, response=response),
@@ -52,7 +54,7 @@ def sync_detailed(
     *,
     client: AuthenticatedClient | Client,
     body: OptionalBodyBody | Unset = UNSET,
-) -> Response[Any]:
+) -> Response[Any, http.HTTPStatus]:
     """Test optional request body
 
     Args:
@@ -81,7 +83,7 @@ async def asyncio_detailed(
     *,
     client: AuthenticatedClient | Client,
     body: OptionalBodyBody | Unset = UNSET,
-) -> Response[Any]:
+) -> Response[Any, http.HTTPStatus]:
     """Test optional request body
 
     Args:

diff --git a/end_to_end_tests/golden-record/my_test_api_client/api/bodies/post_bodies_multiple.py b/end_to_end_tests/golden-record/my_test_api_client/api/bodies/post_bodies_multiple.py
@@ -1,4 +1,4 @@
-from http import HTTPStatus
+import http
 from typing import Any
 
 import httpx
@@ -57,9 +57,11 @@ def _parse_response(*, client: AuthenticatedClient | Client, response: httpx.Res
         return None
 
 
-def _build_response(*, client: AuthenticatedClient | Client, response: httpx.Response) -> Response[Any]:
+def _build_response(
+    *, client: AuthenticatedClient | Client, response: httpx.Response
+) -> Response[Any, http.HTTPStatus]:
     return Response(
-        status_code=HTTPStatus(response.status_code),
+        status_code=http.HTTPStatus(response.status_code),
         content=response.content,
         headers=response.headers,
         parsed=_parse_response(client=client, response=response),
@@ -70,7 +72,7 @@ def sync_detailed(
     *,
     client: AuthenticatedClient | Client,
     body: PostBodiesMultipleJsonBody | File | PostBodiesMultipleDataBody | PostBodiesMultipleFilesBody | Unset = UNSET,
-) -> Response[Any]:
+) -> Response[Any, http.HTTPStatus]:
     """Test multiple bodies
 
     Args:
@@ -102,7 +104,7 @@ async def asyncio_detailed(
     *,
     client: AuthenticatedClient | Client,
     body: PostBodiesMultipleJsonBody | File | PostBodiesMultipleDataBody | PostBodiesMultipleFilesBody | Unset = UNSET,
-) -> Response[Any]:
+) -> Response[Any, http.HTTPStatus]:
     """Test multiple bodies
 
     Args:

diff --git a/end_to_end_tests/golden-record/my_test_api_client/api/bodies/refs.py b/end_to_end_tests/golden-record/my_test_api_client/api/bodies/refs.py
@@ -1,4 +1,4 @@
-from http import HTTPStatus
+import http
 from typing import Any
 
 import httpx
@@ -39,9 +39,11 @@ def _parse_response(*, client: AuthenticatedClient | Client, response: httpx.Res
         return None
 
 
-def _build_response(*, client: AuthenticatedClient | Client, response: httpx.Response) -> Response[Any]:
+def _build_response(
+    *, client: AuthenticatedClient | Client, response: httpx.Response
+) -> Response[Any, http.HTTPStatus]:
     return Response(
-        status_code=HTTPStatus(response.status_code),
+        status_code=http.HTTPStatus(response.status_code),
         content=response.content,
         headers=response.headers,
         parsed=_parse_response(client=client, response=response),
@@ -52,7 +54,7 @@ def sync_detailed(
     *,
     client: AuthenticatedClient | Client,
     body: AModel | Unset = UNSET,
-) -> Response[Any]:
+) -> Response[Any, http.HTTPStatus]:
     """Test request body defined via ref
 
     Args:
@@ -81,7 +83,7 @@ async def asyncio_detailed(
     *,
     client: AuthenticatedClient | Client,
     body: AModel | Unset = UNSET,
-) -> Response[Any]:
+) -> Response[Any, http.HTTPStatus]:
     """Test request body defined via ref
 
     Args:

diff --git a/end_to_end_tests/golden-record/my_test_api_client/api/config/content_type_override.py b/end_to_end_tests/golden-record/my_test_api_client/api/config/content_type_override.py
@@ -1,4 +1,4 @@
-from http import HTTPStatus
+import http
 from typing import Any, cast
 
 import httpx
@@ -39,9 +39,11 @@ def _parse_response(*, client: AuthenticatedClient | Client, response: httpx.Res
         return None
 
 
-def _build_response(*, client: AuthenticatedClient | Client, response: httpx.Response) -> Response[str]:
+def _build_response(
+    *, client: AuthenticatedClient | Client, response: httpx.Response
+) -> Response[str, http.HTTPStatus]:
     return Response(
-        status_code=HTTPStatus(response.status_code),
+        status_code=http.HTTPStatus(response.status_code),
         content=response.content,
         headers=response.headers,
         parsed=_parse_response(client=client, response=response),
@@ -52,7 +54,7 @@ def sync_detailed(
     *,
     client: AuthenticatedClient | Client,
     body: str | Unset = UNSET,
-) -> Response[str]:
+) -> Response[str, http.HTTPStatus]:
     """Content Type Override
 
     Args:
@@ -105,7 +107,7 @@ async def asyncio_detailed(
     *,
     client: AuthenticatedClient | Client,
     body: str | Unset = UNSET,
-) -> Response[str]:
+) -> Response[str, http.HTTPStatus]:
     """Content Type Override
 
     Args:

diff --git a/end_to_end_tests/golden-record/my_test_api_client/api/default/get_common_parameters.py b/end_to_end_tests/golden-record/my_test_api_client/api/default/get_common_parameters.py
@@ -1,4 +1,4 @@
-from http import HTTPStatus
+import http
 from typing import Any
 
 import httpx
@@ -37,9 +37,11 @@ def _parse_response(*, client: AuthenticatedClient | Client, response: httpx.Res
         return None
 
 
-def _build_response(*, client: AuthenticatedClient | Client, response: httpx.Response) -> Response[Any]:
+def _build_response(
+    *, client: AuthenticatedClient | Client, response: httpx.Response
+) -> Response[Any, http.HTTPStatus]:
     return Response(
-        status_code=HTTPStatus(response.status_code),
+        status_code=http.HTTPStatus(response.status_code),
         content=response.content,
         headers=response.headers,
         parsed=_parse_response(client=client, response=response),
@@ -50,7 +52,7 @@ def sync_detailed(
     *,
     client: AuthenticatedClient | Client,
     common: str | Unset = UNSET,
-) -> Response[Any]:
+) -> Response[Any, http.HTTPStatus]:
     """
     Args:
         common (str | Unset):
@@ -78,7 +80,7 @@ async def asyncio_detailed(
     *,
     client: AuthenticatedClient | Client,
     common: str | Unset = UNSET,
-) -> Response[Any]:
+) -> Response[Any, http.HTTPStatus]:
     """
     Args:
         common (str | Unset):

diff --git a/end_to_end_tests/golden-record/my_test_api_client/api/default/get_models_allof.py b/end_to_end_tests/golden-record/my_test_api_client/api/default/get_models_allof.py
@@ -1,4 +1,4 @@
-from http import HTTPStatus
+import http
 from typing import Any
 
 import httpx
@@ -34,9 +34,9 @@ def _parse_response(
 
 def _build_response(
     *, client: AuthenticatedClient | Client, response: httpx.Response
-) -> Response[GetModelsAllofResponse200]:
+) -> Response[GetModelsAllofResponse200, http.HTTPStatus]:
     return Response(
-        status_code=HTTPStatus(response.status_code),
+        status_code=http.HTTPStatus(response.status_code),
         content=response.content,
         headers=response.headers,
         parsed=_parse_response(client=client, response=response),
@@ -46,7 +46,7 @@ def _build_response(
 def sync_detailed(
     *,
     client: AuthenticatedClient | Client,
-) -> Response[GetModelsAllofResponse200]:
+) -> Response[GetModelsAllofResponse200, http.HTTPStatus]:
     """
     Raises:
         errors.UnexpectedStatus: If the server returns an undocumented status code and Client.raise_on_unexpected_status is True.
@@ -86,7 +86,7 @@ def sync(
 async def asyncio_detailed(
     *,
     client: AuthenticatedClient | Client,
-) -> Response[GetModelsAllofResponse200]:
+) -> Response[GetModelsAllofResponse200, http.HTTPStatus]:
     """
     Raises:
         errors.UnexpectedStatus: If the server returns an undocumented status code and Client.raise_on_unexpected_status is True.