The present invention provides the multiuser Multiple-Input Multiple-Output (MIMO) systems with a feedback method which includes measuring, at the terminal, received Signal to Noise Ratios (SNRs) for all transmit antennas, selecting one of precoding matrixes, which has best SNRs, retrieving an index mapped to the selected preceding matrix from a predetermined mapping table, and transmitting the index with the SNRs of the selected precoding matrix. In the present invention, it is possible to reduce feedback information amount without degradation of the sum rate performance of the system since the feedback information is transmitted in a form of index implying appropriate precoding matrix and corresponding SNRs.