Abstract: The error performance for coherent detection transmit antenna selection (AS) system is investigated for a Rayleigh fading channel with imperfect channel state information at the receiver. The symbol error rate (SER) performance is expressed in numerical integration with finite limits for different signaling. Simulation shows that the proposed theoretical result matches the real system performance whether with perfect or imperfect channel information. The numerical results also show that the quality of channel state information dominates the AS system performance in lower signal to noise ratio (SNR) region.