i do have a class where i use fields of type enum and get a java.io.NotSerializableException. As all the other fields are of a simple type (int, etc), i don't know, why this class isn't serializeable/remoteable. Maybe the enum is the problem. The class 'NoteImpl' is transfered between a client and a server using RMI. The class 'Note' is the interface, containing all method definitions, which is required for Java-RMI.