Abstract. We describe, analyze and submit results of a real-time total order multicast protocol developed on a distributed real-time system architecture that consists of hierarchical rings with synchronous packet delivering characteristics. The protocol is structured on and closely interacts with the distributed clock synchronization and the real-time group management modules. The synchronous characteristics of the protocol makes it suitable for hard real-time applications where total ordering is required. The complexity analysis of the protocol is given and the performance results are shown for several scenarios. We show that the developed protocol is correct, scalable and real-time . . .