Space-time block coded spatial modulation (STBCSM) system is the multiple input multiple output (MIMO) communication system that gives better error performance than space-time block coded (STBC) MIMO system when compared at the same spectral efficiency. It performs better than spatial modulation (SM) MIMO systems. In this paper, we analyze the bit error probability (BEP) of STBC-SM systems over correlated Rayleigh and Rician fading channels. A closed form expression for upper bound on the BEP is derived and evaluated. The analytical results are validated using Monte Carlo simulation results. The performance of STBC-SM system is also compared with STBC systems and SM systems in correlated and uncorrelated fading channels.