Wireless ATM is a technology for creating broadband service networks that can transmit voice, data and video via wireless media. Wireless ATM is designed to provide high-speed, noiseless, reliable and asynchronous communications for wireless networks. The medium access control (MAC) layer of LAN protocol architecture standard is corresponding to a subset of data link layer in OSI 7-Layer Reference Model. The layer is very important in wireless environment for controlling multiple accesses to the medium simultaneously. Many MAC protocols were proposed for wireless ATM. Seven of them are studied in this paper. They are DQRUMA, PRMA/DA, DSA++, DTDMA/PR, MASCARA, PRMA/ATDD and DTDMA/TDD. We compare them on architecture, function, and performance aspects. It is our judgment that the best MAC protocol on architecture is DTDMA/TDD; the best one on function is MASCARA; and the best on performance is DTDMA/TDD. It is concluded that DTDMA/TDD is the best MAC protocol considered in this study. Finally, some suggestions are made to the MAC protocol for wireless ATM.