This paper investigates the channel assignment problem of dual-band PCS systems where single-band and dual-band handsets co-exist. Load-balancing channel assignment schemes are proposed to improve the system performance. To balance the loads of both bands, the BSC selects a band to serve a call request of a dual-band handset based on the loads of both bands. In addition, a channel re-assignment scheme is used to further improve the system capacity. Analytic models and computer simulations have been developed to evaluate the performance of the load-balancing schemes. The results indicate that both load-balancing and channel re-assignment techniques significantly increase the system capacity as the percentage of dual-band handsets increases. Furthermore, the load-balancing with channel re-assignment scheme that combines both techniques achieves the best system performance even when the percentage of dual-band handset is as low as 25%. In addition, we describe an approach to reduce the signal overhead of the load-balancing schemes.