This paper introduces a distributed MAC protocol which can provide delay-bounded service in wireless ad hoc networks. Ad hoc networks are network architectures that do not rely on a pre-existing fixed infrastructure, which imposes heavy challenges on designing MAC scheme with QoS support. Most existing MAC protocols for wireless ad hoc networks have been designed to support none-delay-sensitive applications. Given an increasing demand on supporting multimedia applications, there is much interest in designing MAC schemes to satisfy the requirements of real-time applications in ad hoc environments. The timed token based MAC scheme proposed in this paper allocates the bandwidth to the users according to their requirements. This scheme can guarantee the deadline of real-time traffic even in the case of heavy traffic load. In addition, a logical token-passing tree structure adopted in this scheme overcomes the hidden terminal problems in ad hoc networks.