diff --git a/src/agents/memory/openai_conversations_session.py b/src/agents/memory/openai_conversations_session.py
index ce0621358..6a14e81a0 100644
--- a/src/agents/memory/openai_conversations_session.py
+++ b/src/agents/memory/openai_conversations_session.py
@@ -50,7 +50,7 @@ async def get_items(self, limit: int | None = None) -> list[TResponseInputItem]:
                 order="asc",
             ):
                 # calling model_dump() to make this serializable
-                all_items.append(item.model_dump())
+                all_items.append(item.model_dump(exclude_unset=True))
         else:
             async for item in self._openai_client.conversations.items.list(
                 conversation_id=session_id,
@@ -58,7 +58,7 @@ async def get_items(self, limit: int | None = None) -> list[TResponseInputItem]:
                 order="desc",
             ):
                 # calling model_dump() to make this serializable
-                all_items.append(item.model_dump())
+                all_items.append(item.model_dump(exclude_unset=True))
                 if limit is not None and len(all_items) >= limit:
                     break
             all_items.reverse()