It is necessary to apply SSB modulation method with high bandwidth efficiency to the DS-CDMA mobile communication systems in order to accommodate the increasing number of voice users as well as the broad band and high data rate service in the future. Even though the bandwidth efficiency increases if SSB modulation is applied to BPSK-DS/CDMA, its performance gets degraded because of the increased multiple access interference. Therefore for eliminating the increased multiple access interference, the SSB/BPSK-DS/CDMA with successive interference canceller(SIC) is proposed and its performance and capacity are analyzed. With the limited system bandwidth, it is shown that the SSB/BPSK-DS/CDMA with SIC can accommodate more capacity than the conventional BPSK-DS/CDMA with SIC.