diff --git a/ryu/controller/ofp_event.py b/ryu/controller/ofp_event.py
index 6b1c8b3e..6eb8e5f8 100644
--- a/ryu/controller/ofp_event.py
+++ b/ryu/controller/ofp_event.py
@@ -19,10 +19,10 @@ OpenFlow event definitions.
 """
 
 import inspect
+import time
 
 from ryu.controller import handler
 from ryu import ofproto
-from ryu import utils
 from . import event
 
 
@@ -41,12 +41,14 @@ class EventOFPMsgBase(event.EventBase):
     msg.datapath A ryu.controller.controller.Datapath instance
                  which describes an OpenFlow switch from which we received
                  this OpenFlow message.
+    timestamp    Timestamp when Datapath instance generated this event.
     ============ ==============================================================
 
     The msg object has some more additional members whose values are extracted
     from the original OpenFlow message.
     """
     def __init__(self, msg):
+        self.timestamp = time.time()
         super(EventOFPMsgBase, self).__init__()
         self.msg = msg