Abstract-In this paper, we investigate and analyze the performance of amplify and forward (AF) gateways employing zero-forcing (ZF) beamforming techniques in a space division multiple access (SDMA) scenario. A random number of users are isolated from their destination(s) and the only means to communicate with their destination(s) is through the AF gateway equipped with multiple antennas and employing ZF beamforming technique. All forward and backward channels experience small as well as large-scale fading. New exact analytical expressions are derived for the overall spectral efficiency (SE) in the collaborative and non-collaborative SDMA scenarios. In the latter case ZF is implemented at the gateway only. Whereas with regards to the collaborative scenario, ZF is applied at both, the sources and the destinations. The new results are used to investigate the impact of different system parameters on the overall efficiency of ZF AF gateways. The accuracy of the new results is confirmed through Monte Carlo simulations.Index Terms-Amplify and Forward (AF), Multiple-input multiple-output (MIMO), spectral efficiency, space division multiple access (SDMA), zero-forcing (ZF).