Performance analysis is presented for multiple-input multiple-output (MIMO) relay channels with transmit antenna selection and maximal-ratio combining receive (TAS/MRC) in two-hop amplify-and-forward (AF) relay networks operating over flat Rayleigh fading channels, where the source and destination are equipped with Ns and Nj antennas, respectively, and communicate with each other with the help of a single-antenna relay. We derive closed form expressions for the cumulative distribution function (CDF) and probability density function (PDF) of the overall system SNR, based on which we present exact symbol error rate (SER) and outage performance analysis. The theoretical analysis is validated by Monte Carlo simulations, which show an exact match between them. Our analysis shows that full spatial diversity order, which corresponds to the minimum number of antennas at the source and destination, i.e., min{N _s,N _d}, can be achieved for the two-hop AF MIMO relay channel with TAS/MRC.