One way to improve the throughput of a wireless ad hoc network at the media access (MAC) layer is to allow concurrent transmission among neighboring nodes as much as possible. In this paper, we present a novel high-throughput MAC protocol, called CTMAC, that supports concurrent transmission while letting the MANET enjoy the simple design with a single channel, single transceiver, and single transmission power architecture. CTMAC inserts additional control gap between the transmission of control packets (RTS/CTS) and data packet (DATA/ACK), which allows a serious of RTS/CTS exchanges to take place before the possible multiple, concurrent data transmissions. To ensure that concurrent data transmission finishes correctly, the collision avoidance information is included in control packets, and used by neighboring nodes to determine whether begin their transmissions or not. Simulation results show that a significant gain in throughput can be obtained by CTMAC protocol compared with the IEEE 802.11 MAC protocol.