In this paper we propose a novel behavioral model for multiple input, multiple output (MIMO) nonlinear transmitters in the presence of I/Q modulator's imperfections. A joint model is proposed for hardware impairments and distortion of MIMO wireless transmitters. These imperfections originate from the modulator's I/Q imbalance, DC offset, PA's nonlinearity and the crosstalk or coupling effects induced by the interference between the different paths of the transmitter. The performance of the proposed model was evaluated for different cases of modulator's impairments and distortion.