In this paper, error performance of a serially concatenated QPSK space-time system is investigated on quasi-static, block and rapid fading channels. We consider outer nonrecursive convolutional and inner recursive space-time trellis code case and iterative decoding based on the maximum a posteriori (MAP) algorithm. The performance is evaluated by means of computer simulations and it is observed that when the recursive versions of some of the previously known space-time trellis codes are used as the inner codes, the Euclidean distance criterion based space-time codes lead to better error performance for both quasi-static and rapid fading channels. We also investigate the effects of various system parameters on the performance. We obtain the error performance for the large number of transmit and/or receive antennas and observe that, generally, as the number of antennas increases the error performance improves.