In this letter, we consider the effect of macrodiversity on the performance of maximum likelihood detection in flat Rayleigh/Rician fading. Macrodiversity MIMO, where both the transmit antennas and receive antennas are widely separated, is becoming increasingly important with the advent of network MIMO, edge excited cells, base station cooperation, etc. The analysis builds on an exact evaluation of the pairwise error probability which leads to a union bound for symbol error rate (SER). SER results are shown, as well as a diversity analysis and an investigation of the impact of macrodiversity. © 2012 IEEE.