diff --git a/src/error.rs b/src/error.rs
index 32f6291fe3..5a2d448869 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -16,6 +16,7 @@ use self::Error::{
     Header,
     Status,
     Timeout,
+    Upgrade,
     Io,
     TooLarge,
     Incomplete,
@@ -44,6 +45,8 @@ pub enum Error {
     Status,
     /// A timeout occurred waiting for an IO event.
     Timeout,
+    /// A protocol upgrade was encountered, but not yet supported in hyper.
+    Upgrade,
     /// An `io::Error` that occurred while trying to read or write to a network stream.
     Io(IoError),
     /// Parsing a field as string failed
@@ -76,13 +79,14 @@ impl fmt::Display for Error {
 impl StdError for Error {
     fn description(&self) -> &str {
         match *self {
-            Method => "Invalid Method specified",
-            Version => "Invalid HTTP version specified",
-            Header => "Invalid Header provided",
-            TooLarge => "Message head is too large",
-            Status => "Invalid Status provided",
-            Incomplete => "Message is incomplete",
-            Timeout => "Timeout",
+            Method => "invalid Method specified",
+            Version => "invalid HTTP version specified",
+            Header => "invalid Header provided",
+            TooLarge => "message head is too large",
+            Status => "invalid Status provided",
+            Incomplete => "message is incomplete",
+            Timeout => "timeout",
+            Upgrade => "unsupported protocol upgrade",
             Uri(ref e) => e.description(),
             Io(ref e) => e.description(),
             Utf8(ref e) => e.description(),
diff --git a/src/proto/conn.rs b/src/proto/conn.rs
index bda987f400..5f572db327 100644
--- a/src/proto/conn.rs
+++ b/src/proto/conn.rs
@@ -171,65 +171,71 @@ where I: AsyncRead + AsyncWrite,
         debug_assert!(self.can_read_head());
         trace!("Conn::read_head");
 
-        let (version, head) = match self.io.parse::<T>() {
-            Ok(Async::Ready(head)) => (head.version, head),
-            Ok(Async::NotReady) => return Ok(Async::NotReady),
-            Err(e) => {
-                // If we are currently waiting on a message, then an empty
-                // message should be reported as an error. If not, it is just
-                // the connection closing gracefully.
-                let must_error = self.should_error_on_eof();
-                self.state.close_read();
-                self.io.consume_leading_lines();
-                let was_mid_parse = !self.io.read_buf().is_empty();
-                return if was_mid_parse || must_error {
-                    debug!("parse error ({}) with {} bytes", e, self.io.read_buf().len());
-                    Err(e)
-                } else {
-                    debug!("read eof");
-                    Ok(Async::Ready(None))
-                };
-            }
-        };
+        loop {
+            let (version, head) = match self.io.parse::<T>() {
+                Ok(Async::Ready(head)) => (head.version, head),
+                Ok(Async::NotReady) => return Ok(Async::NotReady),
+                Err(e) => {
+                    // If we are currently waiting on a message, then an empty
+                    // message should be reported as an error. If not, it is just
+                    // the connection closing gracefully.
+                    let must_error = self.should_error_on_eof();
+                    self.state.close_read();
+                    self.io.consume_leading_lines();
+                    let was_mid_parse = !self.io.read_buf().is_empty();
+                    return if was_mid_parse || must_error {
+                        debug!("parse error ({}) with {} bytes", e, self.io.read_buf().len());
+                        Err(e)
+                    } else {
+                        debug!("read eof");
+                        Ok(Async::Ready(None))
+                    };
+                }
+            };
 
-        self.state.version = match version {
-            HttpVersion::Http10 => Version::Http10,
-            HttpVersion::Http11 => Version::Http11,
-            _ => {
-                error!("unimplemented HTTP Version = {:?}", version);
-                self.state.close_read();
-                return Err(::Error::Version);
-            }
-        };
+            self.state.version = match version {
+                HttpVersion::Http10 => Version::Http10,
+                HttpVersion::Http11 => Version::Http11,
+                _ => {
+                    error!("unimplemented HTTP Version = {:?}", version);
+                    self.state.close_read();
+                    return Err(::Error::Version);
+                }
+            };
 
-        let decoder = match T::decoder(&head, &mut self.state.method) {
-            Ok(d) => d,
-            Err(e) => {
-                debug!("decoder error = {:?}", e);
-                self.state.close_read();
-                return Err(e);
-            }
-        };
+            let decoder = match T::decoder(&head, &mut self.state.method) {
+                Ok(Some(d)) => d,
+                Ok(None) => {
+                    // likely a 1xx message that we can ignore
+                    continue;
+                }
+                Err(e) => {
+                    debug!("decoder error = {:?}", e);
+                    self.state.close_read();
+                    return Err(e);
+                }
+            };
 
-        debug!("incoming body is {}", decoder);
+            debug!("incoming body is {}", decoder);
 
-        self.state.busy();
-        if head.expecting_continue() {
-            let msg = b"HTTP/1.1 100 Continue\r\n\r\n";
-            self.state.writing = Writing::Continue(Cursor::new(msg));
-        }
-        let wants_keep_alive = head.should_keep_alive();
-        self.state.keep_alive &= wants_keep_alive;
-        let (body, reading) = if decoder.is_eof() {
-            (false, Reading::KeepAlive)
-        } else {
-            (true, Reading::Body(decoder))
-        };
-        self.state.reading = reading;
-        if !body {
-            self.try_keep_alive();
+            self.state.busy();
+            if head.expecting_continue() {
+                let msg = b"HTTP/1.1 100 Continue\r\n\r\n";
+                self.state.writing = Writing::Continue(Cursor::new(msg));
+            }
+            let wants_keep_alive = head.should_keep_alive();
+            self.state.keep_alive &= wants_keep_alive;
+            let (body, reading) = if decoder.is_eof() {
+                (false, Reading::KeepAlive)
+            } else {
+                (true, Reading::Body(decoder))
+            };
+            self.state.reading = reading;
+            if !body {
+                self.try_keep_alive();
+            }
+            return Ok(Async::Ready(Some((head, body))));
         }
-        Ok(Async::Ready(Some((head, body))))
     }
 
     pub fn read_body(&mut self) -> Poll<Option<super::Chunk>, io::Error> {
diff --git a/src/proto/h1/parse.rs b/src/proto/h1/parse.rs
index 0050394405..3c6363b623 100644
--- a/src/proto/h1/parse.rs
+++ b/src/proto/h1/parse.rs
@@ -72,7 +72,7 @@ impl Http1Transaction for ServerTransaction {
         }, len)))
     }
 
-    fn decoder(head: &MessageHead<Self::Incoming>, method: &mut Option<Method>) -> ::Result<Decoder> {
+    fn decoder(head: &MessageHead<Self::Incoming>, method: &mut Option<Method>) -> ::Result<Option<Decoder>> {
         use ::header;
 
         *method = Some(head.subject.0.clone());
@@ -91,19 +91,22 @@ impl Http1Transaction for ServerTransaction {
             // If Transfer-Encoding header is present, and 'chunked' is
             // not the final encoding, and this is a Request, then it is
             // mal-formed. A server should respond with 400 Bad Request.
-            if encodings.last() == Some(&header::Encoding::Chunked) {
-                Ok(Decoder::chunked())
+            if head.version == Http10 {
+                debug!("HTTP/1.0 has Transfer-Encoding header");
+                Err(::Error::Header)
+            } else if encodings.last() == Some(&header::Encoding::Chunked) {
+                Ok(Some(Decoder::chunked()))
             } else {
                 debug!("request with transfer-encoding header, but not chunked, bad request");
                 Err(::Error::Header)
             }
         } else if let Some(&header::ContentLength(len)) = head.headers.get() {
-            Ok(Decoder::length(len))
+            Ok(Some(Decoder::length(len)))
         } else if head.headers.has::<header::ContentLength>() {
             debug!("illegal Content-Length: {:?}", head.headers.get_raw("Content-Length"));
             Err(::Error::Header)
         } else {
-            Ok(Decoder::length(0))
+            Ok(Some(Decoder::length(0)))
         }
     }
 
@@ -225,7 +228,7 @@ impl Http1Transaction for ClientTransaction {
         }, len)))
     }
 
-    fn decoder(inc: &MessageHead<Self::Incoming>, method: &mut Option<Method>) -> ::Result<Decoder> {
+    fn decoder(inc: &MessageHead<Self::Incoming>, method: &mut Option<Method>) -> ::Result<Option<Decoder>> {
         // According to https://tools.ietf.org/html/rfc7230#section-3.3.3
         // 1. HEAD responses, and Status 1xx, 204, and 304 cannot have a body.
         // 2. Status 2xx to a CONNECT cannot have a body.
@@ -235,13 +238,26 @@ impl Http1Transaction for ClientTransaction {
         // 6. (irrelevant to Response)
         // 7. Read till EOF.
 
+        match inc.subject.0 {
+            101 => {
+                debug!("received 101 upgrade response, not supported");
+                return Err(::Error::Upgrade);
+            },
+            100...199 => {
+                trace!("ignoring informational response: {}", inc.subject.0);
+                return Ok(None);
+            },
+            204 |
+            304 => return Ok(Some(Decoder::length(0))),
+            _ => (),
+        }
         match *method {
             Some(Method::Head) => {
-                return Ok(Decoder::length(0));
+                return Ok(Some(Decoder::length(0)));
             }
             Some(Method::Connect) => match inc.subject.0 {
                 200...299 => {
-                    return Ok(Decoder::length(0));
+                    return Ok(Some(Decoder::length(0)));
                 },
                 _ => {},
             },
@@ -251,28 +267,25 @@ impl Http1Transaction for ClientTransaction {
             }
         }
 
-        match inc.subject.0 {
-            100...199 |
-            204 |
-            304 => return Ok(Decoder::length(0)),
-            _ => (),
-        }
 
         if let Some(&header::TransferEncoding(ref codings)) = inc.headers.get() {
-            if codings.last() == Some(&header::Encoding::Chunked) {
-                Ok(Decoder::chunked())
+            if inc.version == Http10 {
+                debug!("HTTP/1.0 has Transfer-Encoding header");
+                Err(::Error::Header)
+            } else if codings.last() == Some(&header::Encoding::Chunked) {
+                Ok(Some(Decoder::chunked()))
             } else {
                 trace!("not chunked. read till eof");
-                Ok(Decoder::eof())
+                Ok(Some(Decoder::eof()))
             }
         } else if let Some(&header::ContentLength(len)) = inc.headers.get() {
-            Ok(Decoder::length(len))
+            Ok(Some(Decoder::length(len)))
         } else if inc.headers.has::<header::ContentLength>() {
             debug!("illegal Content-Length: {:?}", inc.headers.get_raw("Content-Length"));
             Err(::Error::Header)
         } else {
             trace!("neither Transfer-Encoding nor Content-Length");
-            Ok(Decoder::eof())
+            Ok(Some(Decoder::eof()))
         }
     }
 
@@ -460,24 +473,24 @@ mod tests {
         let mut head = MessageHead::<::proto::RequestLine>::default();
 
         head.subject.0 = ::Method::Get;
-        assert_eq!(Decoder::length(0), ServerTransaction::decoder(&head, method).unwrap());
+        assert_eq!(Decoder::length(0), ServerTransaction::decoder(&head, method).unwrap().unwrap());
         assert_eq!(*method, Some(::Method::Get));
 
         head.subject.0 = ::Method::Post;
-        assert_eq!(Decoder::length(0), ServerTransaction::decoder(&head, method).unwrap());
+        assert_eq!(Decoder::length(0), ServerTransaction::decoder(&head, method).unwrap().unwrap());
         assert_eq!(*method, Some(::Method::Post));
 
         head.headers.set(TransferEncoding::chunked());
-        assert_eq!(Decoder::chunked(), ServerTransaction::decoder(&head, method).unwrap());
+        assert_eq!(Decoder::chunked(), ServerTransaction::decoder(&head, method).unwrap().unwrap());
         // transfer-encoding and content-length = chunked
         head.headers.set(ContentLength(10));
-        assert_eq!(Decoder::chunked(), ServerTransaction::decoder(&head, method).unwrap());
+        assert_eq!(Decoder::chunked(), ServerTransaction::decoder(&head, method).unwrap().unwrap());
 
         head.headers.remove::<TransferEncoding>();
-        assert_eq!(Decoder::length(10), ServerTransaction::decoder(&head, method).unwrap());
+        assert_eq!(Decoder::length(10), ServerTransaction::decoder(&head, method).unwrap().unwrap());
 
         head.headers.set_raw("Content-Length", vec![b"5".to_vec(), b"5".to_vec()]);
-        assert_eq!(Decoder::length(5), ServerTransaction::decoder(&head, method).unwrap());
+        assert_eq!(Decoder::length(5), ServerTransaction::decoder(&head, method).unwrap().unwrap());
 
         head.headers.set_raw("Content-Length", vec![b"10".to_vec(), b"11".to_vec()]);
         ServerTransaction::decoder(&head, method).unwrap_err();
@@ -486,6 +499,21 @@ mod tests {
 
         head.headers.set_raw("Transfer-Encoding", "gzip");
         ServerTransaction::decoder(&head, method).unwrap_err();
+
+
+        // http/1.0
+        head.version = ::HttpVersion::Http10;
+        head.headers.clear();
+
+        // 1.0 requests can only have bodies if content-length is set
+        assert_eq!(Decoder::length(0), ServerTransaction::decoder(&head, method).unwrap().unwrap());
+
+        head.headers.set(TransferEncoding::chunked());
+        ServerTransaction::decoder(&head, method).unwrap_err();
+        head.headers.remove::<TransferEncoding>();
+
+        head.headers.set(ContentLength(15));
+        assert_eq!(Decoder::length(15), ServerTransaction::decoder(&head, method).unwrap().unwrap());
     }
 
     #[test]
@@ -496,43 +524,64 @@ mod tests {
         let mut head = MessageHead::<::proto::RawStatus>::default();
 
         head.subject.0 = 204;
-        assert_eq!(Decoder::length(0), ClientTransaction::decoder(&head, method).unwrap());
+        assert_eq!(Decoder::length(0), ClientTransaction::decoder(&head, method).unwrap().unwrap());
         head.subject.0 = 304;
-        assert_eq!(Decoder::length(0), ClientTransaction::decoder(&head, method).unwrap());
+        assert_eq!(Decoder::length(0), ClientTransaction::decoder(&head, method).unwrap().unwrap());
 
         head.subject.0 = 200;
-        assert_eq!(Decoder::eof(), ClientTransaction::decoder(&head, method).unwrap());
+        assert_eq!(Decoder::eof(), ClientTransaction::decoder(&head, method).unwrap().unwrap());
 
         *method = Some(::Method::Head);
-        assert_eq!(Decoder::length(0), ClientTransaction::decoder(&head, method).unwrap());
+        assert_eq!(Decoder::length(0), ClientTransaction::decoder(&head, method).unwrap().unwrap());
 
         *method = Some(::Method::Connect);
-        assert_eq!(Decoder::length(0), ClientTransaction::decoder(&head, method).unwrap());
+        assert_eq!(Decoder::length(0), ClientTransaction::decoder(&head, method).unwrap().unwrap());
 
 
         // CONNECT receiving non 200 can have a body
         head.subject.0 = 404;
         head.headers.set(ContentLength(10));
-        assert_eq!(Decoder::length(10), ClientTransaction::decoder(&head, method).unwrap());
+        assert_eq!(Decoder::length(10), ClientTransaction::decoder(&head, method).unwrap().unwrap());
         head.headers.remove::<ContentLength>();
 
 
         *method = Some(::Method::Get);
         head.headers.set(TransferEncoding::chunked());
-        assert_eq!(Decoder::chunked(), ClientTransaction::decoder(&head, method).unwrap());
+        assert_eq!(Decoder::chunked(), ClientTransaction::decoder(&head, method).unwrap().unwrap());
 
         // transfer-encoding and content-length = chunked
         head.headers.set(ContentLength(10));
-        assert_eq!(Decoder::chunked(), ClientTransaction::decoder(&head, method).unwrap());
+        assert_eq!(Decoder::chunked(), ClientTransaction::decoder(&head, method).unwrap().unwrap());
 
         head.headers.remove::<TransferEncoding>();
-        assert_eq!(Decoder::length(10), ClientTransaction::decoder(&head, method).unwrap());
+        assert_eq!(Decoder::length(10), ClientTransaction::decoder(&head, method).unwrap().unwrap());
 
         head.headers.set_raw("Content-Length", vec![b"5".to_vec(), b"5".to_vec()]);
-        assert_eq!(Decoder::length(5), ClientTransaction::decoder(&head, method).unwrap());
+        assert_eq!(Decoder::length(5), ClientTransaction::decoder(&head, method).unwrap().unwrap());
 
         head.headers.set_raw("Content-Length", vec![b"10".to_vec(), b"11".to_vec()]);
         ClientTransaction::decoder(&head, method).unwrap_err();
+        head.headers.clear();
+
+        // 1xx status codes
+        head.subject.0 = 100;
+        assert!(ClientTransaction::decoder(&head, method).unwrap().is_none());
+
+        head.subject.0 = 103;
+        assert!(ClientTransaction::decoder(&head, method).unwrap().is_none());
+
+        // 101 upgrade not supported yet
+        head.subject.0 = 101;
+        ClientTransaction::decoder(&head, method).unwrap_err();
+        head.subject.0 = 200;
+
+        // http/1.0
+        head.version = ::HttpVersion::Http10;
+
+        assert_eq!(Decoder::eof(), ClientTransaction::decoder(&head, method).unwrap().unwrap());
+
+        head.headers.set(TransferEncoding::chunked());
+        ClientTransaction::decoder(&head, method).unwrap_err();
     }
 
     #[cfg(feature = "nightly")]
diff --git a/src/proto/mod.rs b/src/proto/mod.rs
index b165492855..5bd8ead5b3 100644
--- a/src/proto/mod.rs
+++ b/src/proto/mod.rs
@@ -147,7 +147,7 @@ pub trait Http1Transaction {
     type Incoming;
     type Outgoing: Default;
     fn parse(bytes: &mut BytesMut) -> ParseResult<Self::Incoming>;
-    fn decoder(head: &MessageHead<Self::Incoming>, method: &mut Option<::Method>) -> ::Result<h1::Decoder>;
+    fn decoder(head: &MessageHead<Self::Incoming>, method: &mut Option<::Method>) -> ::Result<Option<h1::Decoder>>;
     fn encode(head: MessageHead<Self::Outgoing>, has_body: bool, method: &mut Option<Method>, dst: &mut Vec<u8>) -> h1::Encoder;
 
     fn should_error_on_parse_eof() -> bool;
diff --git a/tests/client.rs b/tests/client.rs
index d77cba32f5..c1f4f2e9d3 100644
--- a/tests/client.rs
+++ b/tests/client.rs
@@ -458,6 +458,72 @@ test! {
 
 }
 
+test! {
+    name: client_100_continue,
+
+    server:
+        expected: "\
+            POST /continue HTTP/1.1\r\n\
+            Host: {addr}\r\n\
+            Content-Length: 7\r\n\
+            \r\n\
+            foo bar\
+            ",
+        reply: "\
+            HTTP/1.1 100 Continue\r\n\
+            \r\n\
+            HTTP/1.1 200 OK\r\n\
+            Content-Length: 0\r\n\
+            \r\n\
+            ",
+
+    client:
+        request:
+            method: Post,
+            url: "http://{addr}/continue",
+            headers: [
+                ContentLength(7),
+            ],
+            body: Some("foo bar"),
+            proxy: false,
+        response:
+            status: Ok,
+            headers: [],
+            body: None,
+}
+
+
+test! {
+    name: client_101_upgrade,
+
+    server:
+        expected: "\
+            GET /upgrade HTTP/1.1\r\n\
+            Host: {addr}\r\n\
+            \r\n\
+            ",
+        reply: "\
+            HTTP/1.1 101 Switching Protocols\r\n\
+            Upgrade: websocket\r\n\
+            Connection: upgrade\r\n\
+            \r\n\
+            ",
+
+    client:
+        request:
+            method: Get,
+            url: "http://{addr}/upgrade",
+            headers: [],
+            body: None,
+            proxy: false,
+        error: |err| match err {
+            &hyper::Error::Upgrade => true,
+            _ => false,
+        },
+
+}
+
+
 #[test]
 fn client_keep_alive() {
     let server = TcpListener::bind("127.0.0.1:0").unwrap();