The authors present performance results for medium access control protocols which are appropriate for voice/data integration in high-bandwidth token-passing networks. They consider two classes of protocols: (1) multiple priority cycle protocols and (2) timed-token protocols. To provide bounded delays for voice packets, both types of protocols use timers to control the data-packet transmissions on to the channel. The effect of the number of active voice sources on the timers' values is discussed. Simulation results are presented indicating that for both protocols the most important performance parameter is the maximum data information that can be carried by the channel, when the number of active voice sources is specified. Analytic formulae are derived which accurately predict the data capacities for both protocols. The derived formulae are used to present the effect of several system parameters on performance as well as to compare the performance of the two types of protocols.