We propose in this paper a novel group detection scheme that we denote by group ordered successive interference cancellation (GOSIC) multiuser detector. We consider a multiuser MIMO CDMA communication system, where each user carries more than one antenna, but is assigned only one spreading signature. Users are then considered as virtual groups. Our proposed receiver consists of ordering these users at the receiver side in order to maximize the overall system performance, and carrying group detection for each one using layered space-time processing. We define and derive the optimal user order based on the group signal to noise ratio (GSNR), and show that not only it is optimal in this sense but also in the sense of asymptotic symmetric energy. We also propose another sub-optimal order in order to overcome the complexity issues. Finally, we compare the performance of our proposed receivers with traditional group serial interference cancellation and conventional layered space-time multiuser architectures, and show that significant improvement is introduced.