This paper proposes an intrasystem interference cancellation technique for spread spectrum multiple access (SSMA) systems to improve the simultaneous operation performance. Theoretical analysis of its performance and experimental results are described. Although thermal noise and interference from other communication systems can not be recovered at the receiver, it is possible to reproduce interchannel interference signals within an SSMA system, because the spreading codes are known to the receiver. The reproduced interference signals are subtracted from the received signal to cancel the interference signals. An interference signal recovery circuit comprises a conventional SSMA demodulator and a re-spread modulator. The interchannel interference power is reduced by a factor of (n-1)/G as compared with a conventional SSMA demodulator where, G is the process gain and n is the number of simultaneously operating channels. Factors degrading interference cancellation performance are carrier phase error, SS code phase error, delay time error, amplitude variation and waveform degradation due to bandwidth limitation. Theoretical considerations and experimental results on the quantitative effect of these factors are presented.