diff --git a/src/agents/model_settings.py b/src/agents/model_settings.py
index f29cfa4a..ed9a0131 100644
--- a/src/agents/model_settings.py
+++ b/src/agents/model_settings.py
@@ -3,6 +3,7 @@
 from dataclasses import dataclass, fields, replace
 from typing import Literal
 
+from openai._types import Body, Query
 from openai.types.shared import Reasoning
 
 
@@ -58,6 +59,14 @@ class ModelSettings:
     """Whether to include usage chunk.
     Defaults to True if not provided."""
 
+    extra_query: Query | None = None
+    """Additional query fields to provide with the request.
+    Defaults to None if not provided."""
+
+    extra_body: Body | None = None
+    """Additional body fields to provide with the request.
+    Defaults to None if not provided."""
+
     def resolve(self, override: ModelSettings | None) -> ModelSettings:
         """Produce a new ModelSettings by overlaying any non-None values from the
         override on top of this instance."""
diff --git a/src/agents/models/openai_chatcompletions.py b/src/agents/models/openai_chatcompletions.py
index 807c6512..267efcaf 100644
--- a/src/agents/models/openai_chatcompletions.py
+++ b/src/agents/models/openai_chatcompletions.py
@@ -540,6 +540,8 @@ async def _fetch_response(
             store=self._non_null_or_not_given(store),
             reasoning_effort=self._non_null_or_not_given(reasoning_effort),
             extra_headers=_HEADERS,
+            extra_query=model_settings.extra_query,
+            extra_body=model_settings.extra_body,
             metadata=self._non_null_or_not_given(model_settings.metadata),
         )
 
diff --git a/src/agents/models/openai_responses.py b/src/agents/models/openai_responses.py
index 06828884..cb5a603f 100644
--- a/src/agents/models/openai_responses.py
+++ b/src/agents/models/openai_responses.py
@@ -245,6 +245,8 @@ async def _fetch_response(
             parallel_tool_calls=parallel_tool_calls,
             stream=stream,
             extra_headers=_HEADERS,
+            extra_query=model_settings.extra_query,
+            extra_body=model_settings.extra_body,
             text=response_format,
             store=self._non_null_or_not_given(model_settings.store),
             reasoning=self._non_null_or_not_given(model_settings.reasoning),