A topology-transparent protocol, called topology-transparent hybrid MAC (TTHM) protocol is proposed for ad hoc networks. The proposed protocol is based on a protocol threading technique which is the basis of the threaded time spread multiple access (T-TSMA) protocol and a hybrid channel access strategy. According to the current network topology and traffic load, the proposed TTHM protocol can control each node to utilize its assigned slots and its non-assigned slots effectively. TTHM protocol is suitable for distributed application since it keeps the advantage of the topology transparency and eliminates the maximum nodal degree constraint. After the TTHM protocol is presented, its performance is analyzed. Simulation results show that the proposed TTHM protocol is better than the T-TSMA protocol.