diff --git a/Network/HTTP/Conduit.hs b/Network/HTTP/Conduit.hs
--- a/Network/HTTP/Conduit.hs
+++ b/Network/HTTP/Conduit.hs
@@ -33,8 +33,6 @@
 --
 -- * Host
 --
--- * Accept-Encoding (not currently set, but client usage of this variable /will/ cause breakage).
---
 -- Any network code on Windows requires some initialization, and the network
 -- library provides withSocketsDo to perform it. Therefore, proper usage of
 -- this library will always involve calling that function at some point.  The
diff --git a/Network/HTTP/Conduit/Request.hs b/Network/HTTP/Conduit/Request.hs
--- a/Network/HTTP/Conduit/Request.hs
+++ b/Network/HTTP/Conduit/Request.hs
@@ -82,6 +82,26 @@
     -- ^ Everything from the host to the query string.
     , queryString :: S.ByteString
     , requestHeaders :: W.RequestHeaders
+    -- ^ Custom HTTP request headers
+    --
+    -- As already stated in the introduction, the Content-Length and Host
+    -- headers are set automatically by this module, and shall not be added to
+    -- requestHeaders.
+    --
+    -- Moreover, the Accept-Encoding header is set implicitly to gzip for
+    -- convenience by default. This behaviour can be overridden if needed, by
+    -- setting the header explicitly to a different value. In order to omit the
+    -- Accept-Header altogether, set it to the empty string \"\". If you need an
+    -- empty Accept-Header (i.e. requesting the identity encoding), set it to a
+    -- non-empty white-space string, e.g. \" \". See RFC 2616 section 14.3 for
+    -- details about the semantics of the Accept-Header field. If you request a
+    -- content-encoding not supported by this module, you will have to decode
+    -- it yourself (see also the 'decompress' field).
+    --
+    -- Note: Multiple header fields with the same field-name will result in
+    -- multiple header fields being sent and therefore it\'s the responsibility
+    -- of the client code to ensure that the rules from RFC 2616 section 4.2
+    -- are honoured.
     , requestBody :: RequestBody m
     , proxy :: Maybe Proxy
     -- ^ Optional HTTP proxy.
@@ -318,12 +338,19 @@
                 else (:) ("Content-Length", S8.pack $ show contentLength')
     contentLengthHeader Nothing = (:) ("Transfer-Encoding", "chunked")
 
+    acceptEncodingHeader =
+        case lookup "Accept-Encoding" $ requestHeaders req of
+            Nothing -> (("Accept-Encoding", "gzip"):)
+            Just "" -> filter (\(k, _) -> k /= "Accept-Encoding")
+            Just _ -> id
+
+    hostHeader = (("Host", hh):)
+
     headerPairs :: W.RequestHeaders
-    headerPairs
-        = ("Host", hh)
-        : ("Accept-Encoding", "gzip")
-        : (contentLengthHeader contentLength)
-          (requestHeaders req)
+    headerPairs = hostHeader
+                $ acceptEncodingHeader
+                $ contentLengthHeader contentLength
+                $ requestHeaders req
 
     builder :: Builder
     builder =
diff --git a/http-conduit.cabal b/http-conduit.cabal
--- a/http-conduit.cabal
+++ b/http-conduit.cabal
@@ -1,5 +1,5 @@
 name:            http-conduit
-version:         1.5.0.2
+version:         1.5.0.3
 license:         BSD3
 license-file:    LICENSE
 author:          Michael Snoyman <michael@snoyman.com>