In recent years, chaotic signals have created a new area in the designation of wideband communication systems. Most of the activity has focused on DS-CDMA systems, in which the conventional pseudo-noise sequences will be replaced by binary chaotic sequences. Unfortunately, despite the advantages of chaotic systems, the performance of most of such designs is not still suitable for wireless channels. In this paper, a new genetic algorithm-based method is suggested for the optimal generation of chaotic sequences in such systems. Simulation results show that our proposed system outperforms the conventional DS-CDMA systems with "maximal length" codes as well as non-optimized chaos-based DS-CDMA systems.