The most discussed multiple access techiniques for the 3G of mobile wireless systems involve some form of CDMA - Code Division Multiple Access- where the users can transmit simultaneously their signals in the same frequency band separable in the receiver by the orthogonality or, quasi- orthogonality, properties of the transmitted signals. Multiuser detectors MUD perform the detection of the desired user signal jointly with the signals transmitted by the remaining users, resulting in a better performance than the conventional CDMA receivers, that treat the interference created by the signals of other users simply as background noise.This work has the objective of investigating the viability of syncrhronous hybrid multiuser detector, wich combines the implementation simplicity and efficiency of the decorrelating multiuser detector in mitigating the multiple access interference with the robustness and high performance of the optimum multiuser detector.In order to avoid the complexity of the optimum multiuser detection scheme it is proposed to combine the signals from the decorrelator output into groups and perform optimal detection of the signals in each group. This approach is known as optimal group detection. Also in this work, a strategy on how to perform the grouping is proposed and explored. This strategy is based on the minimization the bit error probability of the user with the worst performance.Simulation and analytical results show the excellent trade-off between performance and complexity of the proposed optimum multiuser group detector in AWGN channels. The receiver performance is also evaluated in Rayleigh flat fading channels.