Modern wireless communications require an efficient spectrum usage and high channel capacity and throughput. Multiple input and multiple output (MIMO), space-time coding, multi-user detection (MUD) and multicarrier code-division multiple access (MC-CDMA) are possible solutions to achieve spectral efficiency, high channel capacity and robustness against frequency selective fading. In this paper, we combine all these techniques and investigate BER performance. The performance analysis of uplink MIMO MC-CDMA systems with V-BLAST over frequency selective Rayleigh fading channel is investigated under various number of transmit and receive antennas. The simulation results show that MIMO MC-CDMA with V-BLAST multi-user detection provides high data rate and the BER significant improvement when space time block code is applied.