This work focuses on the downlink of a Zero-Forcing (ZF) precoded multiuser multiple-input multiple-output (MU-MIMO) systems where the Base Station (BS) and the users stations (UEs) transmit and receive information symbols, respectively, by selected subset of their antennas. An optimal transmit antenna selection procedure is proposed aiming at the maximization of the detection signal-to-noise ratio and consequent minimization of the detection error probability. A suboptimal search algorithm able to deliver a performance close to the one resulting from the optimal exhaustive search selection is proposed. The receive antenna selection is also performed using a similar optimization criterion. BER performance results, obtained via simulation and semi-analytical approaches, are presented for different scenarios.