The need for serial multicast remote procedure calls (RPCs) arises in many distributed systems. to avoid network bottlenecks and high-latency links, especially when the caller wants to send a large amount of data to multiple callees. In this paper, we present a mathematical model of serial multicast calls in order to understand their performance behavior. Through our evaluations on the real platform, we find our model is very effective in predicting the performance of serial multicast RPCs.