In variable spreading length access code division multiple access (VSL-CDMA) systems, the performance of group successive interference cancellation (GSIC) detector degrades significantly in fading channels, and the decorrelator is too complex to be used in practical systems. In this paper, we propose an improved hybrid interference cancellation scheme with adaptive group allocation (AHIC) for dualrate VSL-CDMA systems. The proposed AHIC detector adaptively groups users based on their received power level. In this way, the high-rate users, especially the weak ones, would not be penalized by MAI from strong low-rate users. Simulation results have shown that the proposed AHIC scheme can achieve the best bit error rate (BER) performance with relatively low computational complexity.