A code-aided technique for the simultaneous suppression of narrow-band interference (NBI) and multiple-access interference (MAI) in direct-sequence code-division multiple-access (DS/CDMA) networks is proposed. This technique is based on the linear minimum mean-square error (MMSE) algorithm for multiuser detection. The performance of this technique against MAI has been considered previously. In this paper, its performance against NBI as well as combined NBI and MAI is addressed. Specifically, the performance of this technique against three types of narrow-band interferers, namely, multitone interferers, autoregressive (AR) interferers, and digital interferers, is analyzed. The NBI suppression performance of this method is then compared with performance bounds of the linear and nonlinear estimator-subtracter NBI suppression techniques. It is seen that this method outperforms all of the previous linear or nonlinear methods of NBI suppression, while simultaneously suppressing the MAI.