diff --git a/src/anthropic/_base_client.py b/src/anthropic/_base_client.py
index e37759cd..b2fe2426 100644
--- a/src/anthropic/_base_client.py
+++ b/src/anthropic/_base_client.py
@@ -1727,9 +1727,14 @@ def iter_raw(self, chunk_size: Optional[int] = None) -> Iterator[bytes]:
         return self.response.iter_raw(chunk_size)
 
     @override
-    def stream_to_file(self, file: str | os.PathLike[str]) -> None:
+    def stream_to_file(
+        self,
+        file: str | os.PathLike[str],
+        *,
+        chunk_size: int | None = None,
+    ) -> None:
         with open(file, mode="wb") as f:
-            for data in self.response.iter_bytes():
+            for data in self.response.iter_bytes(chunk_size):
                 f.write(data)
 
     @override
@@ -1757,10 +1762,15 @@ async def aiter_raw(self, chunk_size: Optional[int] = None) -> AsyncIterator[byt
         return self.response.aiter_raw(chunk_size)
 
     @override
-    async def astream_to_file(self, file: str | os.PathLike[str]) -> None:
+    async def astream_to_file(
+        self,
+        file: str | os.PathLike[str],
+        *,
+        chunk_size: int | None = None,
+    ) -> None:
         path = anyio.Path(file)
         async with await path.open(mode="wb") as f:
-            async for data in self.response.aiter_bytes():
+            async for data in self.response.aiter_bytes(chunk_size):
                 await f.write(data)
 
     @override
diff --git a/src/anthropic/_types.py b/src/anthropic/_types.py
index bc0d8353..fbd6e3af 100644
--- a/src/anthropic/_types.py
+++ b/src/anthropic/_types.py
@@ -123,7 +123,12 @@ def iter_raw(self, chunk_size: Optional[int] = None) -> Iterator[bytes]:
         pass
 
     @abstractmethod
-    def stream_to_file(self, file: str | PathLike[str]) -> None:
+    def stream_to_file(
+        self,
+        file: str | PathLike[str],
+        *,
+        chunk_size: int | None = None,
+    ) -> None:
         """
         Stream the output to the given file.
         """
@@ -172,7 +177,13 @@ async def aiter_raw(self, chunk_size: Optional[int] = None) -> AsyncIterator[byt
         """
         pass
 
-    async def astream_to_file(self, file: str | PathLike[str]) -> None:
+    @abstractmethod
+    async def astream_to_file(
+        self,
+        file: str | PathLike[str],
+        *,
+        chunk_size: int | None = None,
+    ) -> None:
         """
         Stream the output to the given file.
         """