GeoNetworking is a protocol specially designed to provide geographical addressing and forwarding for Cooperative Intelligent Transport Systems (ITS). Unlike advanced messages defined in GeoNetworking, beaconing messages are fundamental to periodically advertise essential information, e.g., a vehicle ITS station's geographical position and speed, to neighbor ITS stations. The beaconing messages should be delivered in a secure manner. Otherwise, geographical addressing and forwarding of GeoNetworking cannot be supported as unauthorized actions from attackers break down cooperative communication between ITS stations. However, security mechanisms for beaconing messages come with overhead that affect the overall performance. This being so, in this paper, we analyze the overhead of secure beaconing messages in terms of packet delivery ratio, delay, and normalized throughput. From the conducted numerical analysis, we demonstrate that 1) three parameters such as the number of ITS stations in a given radio range, the backoff window size, and the message size mainly affect the performance; 2) the delay of secure beaconing message is still acceptable with proper channel bit rates; and 3) the normalized throughput of secure beaconing message is better than that of the basic beaconing message. Copyright © 2011 John Wiley & Sons, Ltd.