In this work, teletraffic performance of a hierarchically overlaid microcell and macrocell structure in a PCS environment is presented. In this system, each group of N microcells is overlaid exclusively by one macrocell. The microcell tier is dedicated to low-mobility users and the macrocell tier is dedicated to both high-mobility users and overflowed low-mobility users from microcells. In general, forced termination is considerably undesirable from the user's viewpoint compared with the occurrence of call blocking. Therefore, handoff calls are given access priority to channels at the macrocell tier. As a priority scheme at the macrocell tier, a partial buffer sharing (PBS) scheme is proposed. As performance measures, call blocking probability, forced termination probability, and carried traffic are derived. Effects of the sizes of a macrocell and of hierarchical cell structure on system performance are discussed. The performance of the PBS scheme is also compared with those of the no priority scheme (NPS) and the first-come-first-service (FCFS) queueing scheme. Numerical results show that the PBS scheme gives the best performance for handoff traffic among the three schemes.