diff --git a/httpx/_types.py b/httpx/_types.py
index 704dfdff..76fa3057 100644
--- a/httpx/_types.py
+++ b/httpx/_types.py
@@ -65,7 +65,7 @@ AuthTypes = Union[
     "Auth",
 ]
 
-RequestContent = Union[str, bytes, Iterable[bytes], AsyncIterable[bytes]]
+RequestContent = Union[str, bytes, bytearray, Iterable[bytes], AsyncIterable[bytes]]
 ResponseContent = Union[str, bytes, Iterable[bytes], AsyncIterable[bytes]]
 ResponseExtensions = Mapping[str, Any]