There are several advantages to spread the spectrum of the signal, which you wish to transmit, over the channel. The major advantages are summarized as follows: The ability to asynchronous multiple access without need for flow control, mitigation of the multipath propagation delay and the inherent ability of spread spectrum to reject interfering signals whose bandwidths are small compared to that of the spread spectrum signal. However, narrow band jamming sources could degrade the performance of the DS/CDMA single user detector by introducing extremely low signal to interference ratio (SIR) at the input of the single user matched filter. This paper provides an adaptive interference canceller (AIC) which effectively reduces the narrow band interference and consequently improves the single user detection capabilities.