Abstract: Blind space-time multiuser detection using a subspace method for synchronous multipath antenna arrays CDMA systems is presented. Fast and stable yet another subspace tracker (FSYAST) is used for adaptive signal-subspace estimation, and the Kalman-type algorithm is employed for adaptive channel estimation of the synchronous multipath antenna array system. Simulation results show that, the proposed space-time MMSE detector has a better performance than other multiuser based on subspace tracking.