diff --git a/httpx/__init__.py b/httpx/__init__.py
index d7fad2dd..35d5975d 100644
--- a/httpx/__init__.py
+++ b/httpx/__init__.py
@@ -26,7 +26,7 @@ from ._exceptions import (
 from ._models import URL, Cookies, Headers, QueryParams, Request, Response
 from ._status_codes import StatusCode, codes
 from ._transports.asgi import ASGIDispatch, ASGITransport
-from ._transports.urllib3 import URLLib3Transport
+from ._transports.urllib3 import URLLib3ProxyTransport, URLLib3Transport
 from ._transports.wsgi import WSGIDispatch, WSGITransport
 
 __all__ = [
@@ -74,6 +74,7 @@ __all__ = [
     "WriteTimeout",
     "URL",
     "URLLib3Transport",
+    "URLLib3ProxyTransport",
     "StatusCode",
     "Cookies",
     "Headers",