diff --git a/congestion/rtt_stats.go b/congestion/rtt_stats.go
index e538c8b6..3dc89e2f 100644
--- a/congestion/rtt_stats.go
+++ b/congestion/rtt_stats.go
@@ -1,7 +1,6 @@
 package congestion
 
 import (
-	"fmt"
 	"math"
 	"time"
 
@@ -85,7 +84,7 @@ func (r *RTTStats) SetRecentMinRTTwindow(recentMinRTTwindow time.Duration) {
 // UpdateRTT updates the RTT based on a new sample.
 func (r *RTTStats) UpdateRTT(sendDelta, ackDelay time.Duration, now time.Time) {
 	if sendDelta == math.MaxInt64 || sendDelta <= 0 {
-		fmt.Printf("Ignoring measured sendDelta, because it's is either infinite, zero, or negative: %d\n", sendDelta/time.Microsecond)
+		utils.Infof("Ignoring measured sendDelta, because it's is either infinite, zero, or negative: %d\n", sendDelta/time.Microsecond)
 		return
 	}
 
diff --git a/example/main.go b/example/main.go
index 789b9a1a..eb5bf128 100644
--- a/example/main.go
+++ b/example/main.go
@@ -9,9 +9,12 @@ import (
 
 	"github.com/lucas-clemente/quic-go/h2quic"
 	"github.com/lucas-clemente/quic-go/testdata"
+	"github.com/lucas-clemente/quic-go/utils"
 )
 
 func main() {
+	utils.SetLogLevel(utils.LogLevelDebug)
+
 	bindTo := flag.String("bind", "localhost", "bind to")
 	certPath := flag.String("certpath", "", "certificate directory")
 	www := flag.String("www", "/var/www", "www data")
diff --git a/h2quic/response_writer.go b/h2quic/response_writer.go
index ece09014..7ece2ab2 100644
--- a/h2quic/response_writer.go
+++ b/h2quic/response_writer.go
@@ -47,7 +47,7 @@ func (w *responseWriter) WriteHeader(status int) {
 		enc.WriteField(hpack.HeaderField{Name: k, Value: v[0]})
 	}
 
-	fmt.Printf("Responding with %d %#v\n", status, w.header)
+	utils.Infof("Responding with %d %#v\n", status, w.header)
 	h2framer := http2.NewFramer(w.headerStream, nil)
 	err := h2framer.WriteHeaders(http2.HeadersFrameParam{
 		StreamID:      uint32(w.dataStreamID),
diff --git a/h2quic/server.go b/h2quic/server.go
index 70ec938b..7fd053ab 100644
--- a/h2quic/server.go
+++ b/h2quic/server.go
@@ -3,7 +3,6 @@ package h2quic
 import (
 	"crypto/tls"
 	"errors"
-	"fmt"
 	"net/http"
 
 	"github.com/lucas-clemente/quic-go"
@@ -49,7 +48,7 @@ func (s *Server) handleStream(session *quic.Session, headerStream utils.Stream)
 	go func() {
 		for {
 			if err := s.handleRequest(session, headerStream, hpackDecoder, h2framer); err != nil {
-				fmt.Printf("error handling h2 request: %s\n", err.Error())
+				utils.Errorf("error handling h2 request: %s\n", err.Error())
 				return
 			}
 		}
@@ -67,7 +66,7 @@ func (s *Server) handleRequest(session *quic.Session, headerStream utils.Stream,
 	}
 	headers, err := hpackDecoder.DecodeFull(h2headersFrame.HeaderBlockFragment())
 	if err != nil {
-		fmt.Printf("invalid http2 headers encoding: %s\n", err.Error())
+		utils.Errorf("invalid http2 headers encoding: %s\n", err.Error())
 		return err
 	}
 
@@ -75,7 +74,7 @@ func (s *Server) handleRequest(session *quic.Session, headerStream utils.Stream,
 	if err != nil {
 		return err
 	}
-	fmt.Printf("Request: %#v\n", req)
+	utils.Infof("Request: %#v\n", req)
 
 	responseWriter := &responseWriter{
 		header:       http.Header{},
diff --git a/server.go b/server.go
index e16701b9..526d93c8 100644
--- a/server.go
+++ b/server.go
@@ -4,12 +4,12 @@ import (
 	"bytes"
 	"crypto/tls"
 	"errors"
-	"fmt"
 	"net"
 
 	"github.com/lucas-clemente/quic-go/crypto"
 	"github.com/lucas-clemente/quic-go/handshake"
 	"github.com/lucas-clemente/quic-go/protocol"
+	"github.com/lucas-clemente/quic-go/utils"
 )
 
 // PacketHandler handles packets
@@ -70,7 +70,7 @@ func (s *Server) ListenAndServe(address string) error {
 		}
 		data = data[:n]
 		if err := s.handlePacket(s.conn, remoteAddr, data); err != nil {
-			fmt.Printf("error handling packet: %s", err.Error())
+			utils.Errorf("error handling packet: %s", err.Error())
 		}
 	}
 }
@@ -93,7 +93,7 @@ func (s *Server) handlePacket(conn *net.UDPConn, remoteAddr *net.UDPAddr, packet
 
 	// Send Version Negotiation Packet if the client is speaking a different protocol version
 	if publicHeader.VersionFlag && !protocol.IsSupportedVersion(publicHeader.VersionNumber) {
-		fmt.Printf("Client offered version %d, sending VersionNegotiationPacket\n", publicHeader.VersionNumber)
+		utils.Infof("Client offered version %d, sending VersionNegotiationPacket\n", publicHeader.VersionNumber)
 		_, err = conn.WriteToUDP(composeVersionNegotiation(publicHeader.ConnectionID), remoteAddr)
 		if err != nil {
 			return err
@@ -103,7 +103,7 @@ func (s *Server) handlePacket(conn *net.UDPConn, remoteAddr *net.UDPAddr, packet
 
 	session, ok := s.sessions[publicHeader.ConnectionID]
 	if !ok {
-		fmt.Printf("Serving new connection: %d from %v\n", publicHeader.ConnectionID, remoteAddr)
+		utils.Infof("Serving new connection: %d from %v\n", publicHeader.ConnectionID, remoteAddr)
 		session = s.newSession(
 			&udpConn{conn: conn, currentAddr: remoteAddr},
 			publicHeader.VersionNumber,
diff --git a/session.go b/session.go
index 3fbcdc2a..1c20ac64 100644
--- a/session.go
+++ b/session.go
@@ -115,7 +115,7 @@ func (s *Session) Run() {
 			case ackhandler.ErrMapAccess:
 				s.Close(err, true) // TODO: sent correct error code here
 			case errRstStreamOnInvalidStream:
-				fmt.Printf("Ignoring error in session: %s\n", err.Error())
+				utils.Errorf("Ignoring error in session: %s\n", err.Error())
 			default:
 				s.Close(err, true)
 			}
@@ -133,7 +133,7 @@ func (s *Session) handlePacket(remoteAddr interface{}, publicHeader *PublicHeade
 		publicHeader.PacketNumber,
 	)
 	s.lastRcvdPacketNumber = publicHeader.PacketNumber
-	fmt.Printf("<- Reading packet 0x%x (%d bytes) for connection %x\n", publicHeader.PacketNumber, r.Size(), publicHeader.ConnectionID)
+	utils.Infof("<- Reading packet 0x%x (%d bytes) for connection %x\n", publicHeader.PacketNumber, r.Size(), publicHeader.ConnectionID)
 
 	// TODO: Only do this after authenticating
 	s.conn.setCurrentRemoteAddr(remoteAddr)
@@ -144,7 +144,7 @@ func (s *Session) handlePacket(remoteAddr interface{}, publicHeader *PublicHeade
 		// instead save them to a queue and retry later.
 		// See issue https://github.com/lucas-clemente/quic-go/issues/38
 		if qErr, ok := err.(*protocol.QuicError); ok && qErr.ErrorCode == errorcodes.QUIC_DECRYPTION_FAILURE {
-			fmt.Println("Discarding packet due to decryption failure.")
+			utils.Infof("Discarding packet due to decryption failure.")
 			return nil // Discard packet
 		}
 		return err
@@ -156,31 +156,31 @@ func (s *Session) handlePacket(remoteAddr interface{}, publicHeader *PublicHeade
 		var err error
 		switch frame := ff.(type) {
 		case *frames.StreamFrame:
-			fmt.Printf("\t<- &frames.StreamFrame{StreamID: %d, FinBit: %t, Offset: %d}\n", frame.StreamID, frame.FinBit, frame.Offset)
+			utils.Debugf("\t<- &frames.StreamFrame{StreamID: %d, FinBit: %t, Offset: %d}\n", frame.StreamID, frame.FinBit, frame.Offset)
 			err = s.handleStreamFrame(frame)
 		case *frames.AckFrame:
 			var duration time.Duration
 			duration, err = s.sentPacketHandler.ReceivedAck(frame)
 			s.rttStats.UpdateRTT(duration, frame.DelayTime, time.Now())
-			fmt.Printf("\t<- %#v\n", frame)
-			fmt.Printf("\tEstimated RTT: %dms\n", s.rttStats.SmoothedRTT()/time.Millisecond)
+			utils.Debugf("\t<- %#v\n", frame)
+			utils.Debugf("\tEstimated RTT: %dms\n", s.rttStats.SmoothedRTT()/time.Millisecond)
 			// ToDo: send right error in ConnectionClose frame
 		case *frames.ConnectionCloseFrame:
-			fmt.Printf("\t<- %#v\n", frame)
+			utils.Debugf("\t<- %#v\n", frame)
 			s.Close(nil, false)
 		case *frames.StopWaitingFrame:
-			fmt.Printf("\t<- %#v\n", frame)
+			utils.Debugf("\t<- %#v\n", frame)
 			err = s.receivedPacketHandler.ReceivedStopWaiting(frame)
 		case *frames.RstStreamFrame:
 			err = s.handleRstStreamFrame(frame)
-			fmt.Printf("\t<- %#v\n", frame)
+			utils.Debugf("\t<- %#v\n", frame)
 		case *frames.WindowUpdateFrame:
-			fmt.Printf("\t<- %#v\n", frame)
+			utils.Debugf("\t<- %#v\n", frame)
 			err = s.handleWindowUpdateFrame(frame)
 		case *frames.BlockedFrame:
-			fmt.Printf("BLOCKED frame received for connection %x stream %d\n", s.connectionID, frame.StreamID)
+			utils.Infof("BLOCKED frame received for connection %x stream %d\n", s.connectionID, frame.StreamID)
 		case *frames.PingFrame:
-			fmt.Printf("\t<- %#v\n", frame)
+			utils.Debugf("\t<- %#v\n", frame)
 		default:
 			panic("unexpected frame type")
 		}
@@ -268,7 +268,7 @@ func (s *Session) Close(e error, sendConnectionClose bool) error {
 	if e == nil {
 		e = protocol.NewQuicError(errorcodes.QUIC_PEER_GOING_AWAY, "peer going away")
 	}
-	fmt.Printf("Closing session with error: %s\n", e.Error())
+	utils.Errorf("Closing session with error: %s\n", e.Error())
 	errorCode := protocol.ErrorCode(1)
 	reasonPhrase := e.Error()
 	quicError, ok := e.(*protocol.QuicError)
@@ -311,7 +311,7 @@ func (s *Session) sendPacket() error {
 	// TODO: handle multiple packets retransmissions
 	retransmitPacket := s.sentPacketHandler.DequeuePacketForRetransmission()
 	if retransmitPacket != nil {
-		fmt.Printf("\tQueueing retransmission for packet 0x%x\n", retransmitPacket.PacketNumber)
+		utils.Infof("\tQueueing retransmission for packet 0x%x\n", retransmitPacket.PacketNumber)
 		s.stopWaitingManager.RegisterPacketForRetransmission(retransmitPacket)
 		// resend the frames that were in the packet
 		controlFrames = append(controlFrames, retransmitPacket.GetControlFramesForRetransmission()...)
@@ -347,12 +347,12 @@ func (s *Session) sendPacket() error {
 
 	s.stopWaitingManager.SentStopWaitingWithPacket(packet.number)
 
-	fmt.Printf("-> Sending packet 0x%x (%d bytes)\n", packet.number, len(packet.raw))
+	utils.Infof("-> Sending packet 0x%x (%d bytes)\n", packet.number, len(packet.raw))
 	for _, frame := range packet.frames {
 		if streamFrame, isStreamFrame := frame.(*frames.StreamFrame); isStreamFrame {
-			fmt.Printf("\t-> &frames.StreamFrame{StreamID: %d, FinBit: %t, Offset: 0x%x, Data length: 0x%x, Offset + Data length: 0x%x}\n", streamFrame.StreamID, streamFrame.FinBit, streamFrame.Offset, len(streamFrame.Data), streamFrame.Offset+uint64(len(streamFrame.Data)))
+			utils.Debugf("\t-> &frames.StreamFrame{StreamID: %d, FinBit: %t, Offset: 0x%x, Data length: 0x%x, Offset + Data length: 0x%x}\n", streamFrame.StreamID, streamFrame.FinBit, streamFrame.Offset, len(streamFrame.Data), streamFrame.Offset+uint64(len(streamFrame.Data)))
 		} else {
-			fmt.Printf("\t-> %#v\n", frame)
+			utils.Debugf("\t-> %#v\n", frame)
 		}
 	}
 
@@ -399,7 +399,7 @@ func (s *Session) garbageCollectStreams() {
 }
 
 func (s *Session) sendPublicReset(rejectedPacketNumber protocol.PacketNumber) error {
-	fmt.Printf("Sending public reset for connection %x, packet number %d\n", s.connectionID, rejectedPacketNumber)
+	utils.Infof("Sending public reset for connection %x, packet number %d\n", s.connectionID, rejectedPacketNumber)
 	packet := &publicResetPacket{
 		connectionID:         s.connectionID,
 		rejectedPacketNumber: rejectedPacketNumber,
diff --git a/utils/log.go b/utils/log.go
new file mode 100644
index 00000000..d2b483a7
--- /dev/null
+++ b/utils/log.go
@@ -0,0 +1,45 @@
+package utils
+
+import "fmt"
+
+// LogLevel of quic-go
+type LogLevel uint8
+
+const (
+	// LogLevelDebug enables debug logs (e.g. packet contents)
+	LogLevelDebug LogLevel = iota
+	// LogLevelInfo enables info logs (e.g. packets)
+	LogLevelInfo
+	// LogLevelError enables err logs
+	LogLevelError
+	// LogLevelNothing disables
+	LogLevelNothing
+)
+
+var logLevel = LogLevelNothing
+
+// SetLogLevel sets the log level
+func SetLogLevel(level LogLevel) {
+	logLevel = level
+}
+
+// Debugf logs something
+func Debugf(format string, args ...interface{}) {
+	if logLevel == LogLevelDebug {
+		fmt.Printf(format+"\n", args...)
+	}
+}
+
+// Infof logs something
+func Infof(format string, args ...interface{}) {
+	if logLevel <= LogLevelInfo {
+		fmt.Printf(format+"\n", args...)
+	}
+}
+
+// Errorf logs something
+func Errorf(format string, args ...interface{}) {
+	if logLevel <= LogLevelError {
+		fmt.Printf(format+"\n", args...)
+	}
+}