— Medium access control (MAC) protocols for wireless packet networks usually need to be distributed for flexibility and robustness. In a distributed way, however, collision detection becomes difficult and collided packets are usually still fully transmitted with existing wireless MAC protocols, which wastes the precious medium resource of the network. This paper proposes a new MAC protocol that realizes effective and efficient collision detection in wireless packet networks by the use of pulses of random-length pauses. Our comprehensive simulation results show the capability of the new protocol for significantly improving the throughput of future wireless packet networks.