Various aspects of a method and a system for finding a threshold for semi-orthogonal user group selection in multiuser MIMO downlink transmission are presented. Aspects of a system for semi-orthogonal user group selection may include a processor that computes an orthogonality measurement between one of a plurality of signals and at least one of a remaining portion of the plurality of signals. The processor may compare each of the orthogonality measurements to a threshold orthogonality value based on a computed probability. The processor may select a user group, based on the threshold orthogonality value, including one of the plurality of signals and one or more signals selected from the remaining portion of the plurality of signals.