Abstract: Background and Objective: Multi-Input Multi-Output (MIMO) systems combined with Orthogonal Frequency Division Multiplexing (OFDM) gained a wide popularity in wireless applications due to the potential of providing increased channel capacity and robustness against multipath fading channels. Methodology: This study distinguishes than the previous study on showing the best code between Alamouti code and OSTBC (Tarokh code) after applying them in multicarrier modulation OFDM and comparing the two combined schemes with some studies that are made previously. Results: More of this, point out the adequate length of IFFT about OFDM and the order of the constellation for PSK and QAM modulation that given a good performance (low BER ) in two combined system. Conclusion: The channel assumed is rayleigh fading that modeled wireless channel, Maximum Likelihood (ML) is used for detection the data at the receiver side.