For Multiple-Input Multiple-Output (MIMO) systems with frequency selective fading channels, Bit-Interleaved Coded Multiple Beamforming (BICMB) with Orthogonal Frequency Division Multiplexing (OFDM) can be employed to offer both spatial and multipath diversity, making it an important technique. Nevertheless, analyzing its diversity is a challenging problem. In this paper, the diversity analysis of BICMB-OFDM is carried out. First, the maximum achievable diversity is derived and a full diversity condition is proved. Then, the performance degradation due to the subcarrier correlation is investigated. Finally, the subcarrier grouping technique is applied to combat the performance degradation and provide multi-user compatibility. © 2013 IEEE.