Medium access control protocols are at the core of all forms of electronic communications systems. MAC protocols are designed to coordinate the transmission of packets, retransmission of damaged packets, and resolution of collisions among stations during a contention period. MAC protocols are foundations in low-level network architecture and play a significant role in the performance of higher-level protocols such as multiservices and multimedia application protocols. In this article five classes of MAC protocols are investigated with respect to their applications in satellite communications. These classes include fixed assignments, demand assignment, random access, hybrid random access and reservation, and adaptive protocols. Among several QoS objectives described in high-speed networking and the limitations inherent in satellite communications systems, in this article a set of important performance criteria are identified and used to evaluate different MAC protocols for satellite communications. The performance criteria include high channel throughput, low transmission delay, channel stability, protocol scalability, channel reconfigurability, broadband applicability, and low complexity of the control algorithm. For this, a simulation study is performed among selected MAC protocols from different classes, and their performances have been evaluated for NASA's Mars Regional Network.