Abstract: Based on the analysis of the correlation properties of variable-length spreading sequences, the performance of the asynchronous multi-rate DS-CDMA system employing orthogonal variable spreading factor (OVSF) sequences is studied. Analytical results of multiple access interference (MAI) are derived in terms of aperiodic partial correlation of the spreading sequences. The numerical results demonstrate that the sequence lengths of interfering users have significant effects on BER performance of desired users, while the effect of sequence length of desired users is negligible.