diff --git a/Network/HTTP/Client.hs b/Network/HTTP/Client.hs
--- a/Network/HTTP/Client.hs
+++ b/Network/HTTP/Client.hs
@@ -89,6 +89,7 @@
     , requestHeaders
     , requestBody
     , proxy
+    , applyBasicProxyAuth
     , decompress
     , redirectCount
     , checkStatus
diff --git a/Network/HTTP/Client/Request.hs b/Network/HTTP/Client/Request.hs
--- a/Network/HTTP/Client/Request.hs
+++ b/Network/HTTP/Client/Request.hs
@@ -14,6 +14,7 @@
     , alwaysDecompress
     , addProxy
     , applyBasicAuth
+    , applyBasicProxyAuth
     , urlEncodedBody
     , needsGunzip
     , requestBuilder
@@ -230,7 +231,6 @@
     authHeader = (CI.mk "Authorization", basic)
     basic = S8.append "Basic " (B64.encode $ S8.concat [ user, ":", passwd ])
 
-
 -- | Add a proxy to the Request so that the Request when executed will use
 -- the provided proxy.
 --
@@ -238,6 +238,20 @@
 addProxy :: S.ByteString -> Int -> Request -> Request
 addProxy hst prt req =
     req { proxy = Just $ Proxy hst prt }
+
+-- | Add a Proxy-Authorization header (with the specified username and
+-- password) to the given 'Request'. Ignore error handling:
+--
+-- > applyBasicProxyAuth "user" "pass" <$> parseUrl "http://example.org"
+--
+-- Since 0.3.4
+
+applyBasicProxyAuth :: S.ByteString -> S.ByteString -> Request -> Request
+applyBasicProxyAuth user passwd req =
+    req { requestHeaders = authHeader : requestHeaders req }
+  where
+    authHeader = (CI.mk "Proxy-Authorization", basic)
+    basic = S8.append "Basic " (B64.encode $ S8.concat [ user , ":", passwd ])
 
 -- | Add url-encoded parameters to the 'Request'.
 --
diff --git a/http-client.cabal b/http-client.cabal
--- a/http-client.cabal
+++ b/http-client.cabal
@@ -1,5 +1,5 @@
 name:                http-client
-version:             0.3.3.2
+version:             0.3.4
 synopsis:            An HTTP client engine, intended as a base layer for more user-friendly packages.
 description:         This codebase has been refactored from http-conduit.
 homepage:            https://github.com/snoyberg/http-client
diff --git a/test/Network/HTTP/Client/RequestSpec.hs b/test/Network/HTTP/Client/RequestSpec.hs
--- a/test/Network/HTTP/Client/RequestSpec.hs
+++ b/test/Network/HTTP/Client/RequestSpec.hs
@@ -1,21 +1,28 @@
 {-# LANGUAGE OverloadedStrings #-}
 module Network.HTTP.Client.RequestSpec where
 
+import Control.Applicative ((<$>))
+import Control.Monad (join)
+import Data.Maybe (isJust)
 import Test.Hspec
-import Network.HTTP.Client (parseUrl)
+import Network.HTTP.Client (parseUrl, requestHeaders, applyBasicProxyAuth)
+import Control.Monad (forM_)
 
 spec :: Spec
-spec = describe "case insensitive scheme" $ do
-    let succeed s = it s $
-            case parseUrl s of
-                Nothing -> error "failed"
-                Just _ -> return () :: IO ()
-        failure s = it s $
-            case parseUrl s of
-                Nothing -> return () :: IO ()
-                Just req -> error $ show req
-    succeed "http://example.com"
-    succeed "httP://example.com"
-    succeed "HttP://example.com"
-    succeed "HttPs://example.com"
-    failure "ftp://example.com"
+spec = do
+  describe "case insensitive scheme" $ do
+    forM_ ["http://example.com", "httP://example.com", "HttP://example.com", "HttPs://example.com"] $ \url ->
+      it url $ case parseUrl url of
+        Nothing -> error "failed"
+        Just _ -> return () :: IO ()
+    forM_ ["ftp://example.com"] $ \url ->
+      it url $ case parseUrl url of
+        Nothing -> return () :: IO ()
+        Just req -> error $ show req
+  describe "applyBasicProxyAuth" $ do
+    let request = applyBasicProxyAuth "user" "pass" <$> parseUrl "http://example.org"
+        field   = join $ lookup "Proxy-Authorization" . requestHeaders <$> request
+    it "Should add a proxy-authorization header" $ do
+      field `shouldSatisfy` isJust
+    it "Should add a proxy-authorization header with the specified username and password." $ do
+      field `shouldBe` Just "Basic dXNlcjpwYXNz"