In this paper we describe a new prioritized protocol for ALOHA in a satellite channel which divides the messages on the channel to two classes : Priority messages (class-A) and non-priority messages (class-B). The scheme is based upon the principle that exclusive access right to the channel is given to class-A messages after each successful transmission from any class of messages [2]. This is accomplished by reserving the channel for a certain period of time during which only class-A messages can contend for the channel. The equilibrium throughput and delay for both classes of messages are obtained and also the effect of reservation period of the channel on class-B messages by using a new language in the network analysis field (QNAP 2).