In this paper, we study the performance of opportunistic scheduling for downlink data transmissions with type-II packet-combining hybrid ARQ in a multirate cellular network for a fast fading environment. We develop a Markov model for a two-user scenario with two feasible transmission rates, and derive the throughput distribution. Numerical results suggest that there exists an operating region within which opportunistic scheduling maintains its scheduling gain over round-robin scheduling; this region disappears when the gap between the transmission rates becomes very large. In ongoing work, we seek to extend the analysis of the model as well as generalize the model to a multi-user scenario.