Efficient medium access control in wireless networks has been a challenging task. While the IEEE 802.11 standard coordinates contention effectively, it severely limits the number of concurrent communications. This results in reduced throughput and efficiency. Recent research has focused on employing multiple antennas to increase throughput in a multipath environment by enabling multiple streams between a transmit-receive pair. In this paper we show that exploiting multiuser diversity to enable concurrent communications has certain advantages over multiple streaming. We propose a medium access control (MAC) protocol that uses adaptive interference cancellation with multiple antennas to increase network throughput and to provide better fairness, while requiring minimal change to the widely-deployed 802.11 MAC structure