We provide new analytical and computer simulation results for the performance of multitone direct-sequence spread spectrum (MT-DS-SS) signaling in the presence of imperfect synchronization, modeled as frequency offset and phase noise. We investigate performance as a function of frequency offset/phase noise standard deviation, number of subcarriers and the per-subcarrier processing gain. We assume coherent detection with BPSK modulation. Comparisons between simulations and analysis show excellent agreement. Our approach offers a realistic analytical/numerical method for performance evaluation when the target error probability values are of the order of 10 −6 or lower. In addition, our method can also be easily applied to any multicarrier system with other frequency offset/phase noise models.