Adaptive antenna arrays at both the base and mobile stations can further increase system capac- ity and improve the quality of service of conventional orthogonal frequency division multiplexing (OFDM) systems. Conventional adaptive antenna array-based multiple-input multiple-output (MIMO)/OFDM systems use the sub-carriers characterized by the largest eigenvalue to transmit the OFDM symbols. This paper de- scribes the performance of adaptive subchannel assignment-based MIMO/OFDM systems over multipath fading channels. The system adaptively selects the eigenvectors associated with the relatively large sub- channel eigenvalues to generate the antenna array weights at the base and mobile stations and then adap- tively assigns the corresponding best subchannels to transmit the OFDM symbols. Simulation results show that the proposed system can achieve better performance than the conventional adaptive antenna array- based MIMO/OFDM system over multipath fading channels. Adaptive antenna arrays at both the base and mobile stations can further increase system capac- ity and improve the quality of service of conventional of orthogonal frequency division multiplexing (OFDM) systems. Conventional adaptive antenna array-based multiple-input multiple-output (MIMO) / OFDM systems use the sub-carriers characterized by the largest eigenvalue to transmit the OFDM symbols. This paper de scribes the performance of adaptive subchannel assignment-based MIMO / OFDM systems over multipath fading channels. The system adaptively selects the eigenvectors associated with the relatively large sub-channel eigenvalues ​​to generate the antenna array weights at the base and mobile stations and then adap- tively assigns the corresponding best subchannels to transmit the OFDM symbols. Simulation results show that the proposed system can achieve better performance than the conventional adaptive antenna array - based MIMO / OFDM system over multipath fading channels.