Index: twisted/internet/interfaces.py
===================================================================
--- twisted/internet/interfaces.py	(revision 28429)
+++ twisted/internet/interfaces.py	(working copy)
@@ -387,7 +387,35 @@
         @return: An object which provides L{IListeningPort}.
         """
 
+class IReactorWin32Events(Interface):
+    """
+    Win32 Event API methods
+    """
+    
+    def addEvent(event, fd, action):
+        """
+        Add a new win32 event to the event loop.
+        
+        @param event: a Win32 event object created using win32event.CreateEvent()
+        
+        @param fd: an instance of L{twisted.internet.abstract.FileDescriptor}
+        
+        @param action: a callable, called in response to the registered event
+        
+        @return: None
+        """
 
+    def removeEvent(event):
+        """
+        Remove an event.
+        
+        @param event: a Win32 event object added using L{IReactorWin32Events.addEvent}
+        
+        @return: None
+        """
+
+
+
 class IReactorUDP(Interface):
     """
     UDP socket methods.
Index: twisted/internet/win32eventreactor.py
===================================================================
--- twisted/internet/win32eventreactor.py	(revision 28429)
+++ twisted/internet/win32eventreactor.py	(working copy)
@@ -57,7 +57,7 @@
 # Twisted imports
 from twisted.internet import posixbase
 from twisted.python import log, threadable, failure
-from twisted.internet.interfaces import IReactorFDSet, IReactorProcess
+from twisted.internet.interfaces import IReactorFDSet, IReactorProcess, IReactorWin32Events
 
 from twisted.internet._dumbwin32proc import Process
 
@@ -76,7 +76,7 @@
     @ivar _events: A dictionary mapping win32 event object to tuples of
         L{FileDescriptor} instances and event masks.
     """
-    implements(IReactorFDSet, IReactorProcess)
+    implements(IReactorFDSet, IReactorProcess, IReactorWin32Events)
 
     dummyEvent = CreateEvent(None, 0, 0, None)
 
Index: twisted/internet/_win32serialport.py
===================================================================
--- twisted/internet/_win32serialport.py	(revision 28429)
+++ twisted/internet/_win32serialport.py	(working copy)
@@ -21,6 +21,7 @@
 from twisted.protocols import basic
 from twisted.internet import abstract
 from twisted.python import log
+from twisted.internet.interfaces import IReactorWin32Events
 
 # sibling imports
 from serialport import BaseSerialPort
@@ -34,6 +35,9 @@
     def __init__(self, protocol, deviceNameOrPortNumber, reactor, 
         baudrate = 9600, bytesize = EIGHTBITS, parity = PARITY_NONE,
         stopbits = STOPBITS_ONE, xonxoff = 0, rtscts = 0):
+
+        assert IReactorWin32Events.providedBy(reactor), "win32eventreactor needs to be installed for use with SerialPort on Win32. e.g.\nfrom twisted.internet import win32eventreactor\nwin32eventreactor.install()"
+        
         self._serial = serial.Serial(deviceNameOrPortNumber, baudrate=baudrate,
                                      bytesize=bytesize, parity=parity,
                                      stopbits=stopbits, timeout=None,
@@ -52,7 +56,7 @@
         self._overlappedRead.hEvent = win32event.CreateEvent(None, 1, 0, None)
         self._overlappedWrite = win32file.OVERLAPPED()
         self._overlappedWrite.hEvent = win32event.CreateEvent(None, 0, 0, None)
-        
+
         self.reactor.addEvent(self._overlappedRead.hEvent, self, 'serialReadEvent')
         self.reactor.addEvent(self._overlappedWrite.hEvent, self, 'serialWriteEvent')