Techniques for communication over flat multi-input, multi-output (MIMO) channels are well established when either perfect channel state information or no channel state information is available at the transmitter. However, communication over channels where the transmitter has access to partial or imperfect information has received less attention. If exploited, such information could improve system performance. In this paper, we propose a simple system design scheme, that approximately maximizes the data rates of MIMO communication systems where imperfect channel estimates are available at the transmitter. The algorithm is computationally attractive and by taking the uncertainty of the channel estimates into account in the design gains compared with systems not exploiting this information can be demonstrated.