One of the major constraints in wireless sensor networks (WSNs) is power consumption. In recent years, a lot of efforts have been put into the design of medium access control (MAC) protocols for WSN, in order to reduce energy consumption and enhance the network’s lifetime. In this paper, we surveyed some MAC protocols for WSN and compared their design tradeoffs. The goal is to provide a foundation for future MAC design, and to identify important design issues that allow us to improve the overall performances