To assess the effects of different cropping systems of sesame and cowpea on cotton productivity, six cropping systems including; fallow-cotton, sesame-cotton, cowpea-cotton, 50-50 sesame/cowpea-cotton, 75-25 sesame/cowpea-cotton and 25-75 sesame / cowpea-cotton were experimented and evaluated using randomized completed block design with Three replications in Fasa, Iran,  in 2014 and 2015. Results showed that in 2014 intercropping of 50:50 sesame-cowpea compared to monocultured was highly superior in terms of land equivalent ratio (1.03), area time equivalent ratio (1.04) and land use efficiency (155%). These findings suggest that specific function of each crop within the intercropping could increase the total productivity of the system.  However, in 2015, results showed that planting cotton after cowpea and 75-25 sesame/cowpea intercrop were more productive than other cropping systems and when compared with fallow-cotton system, and cotton yield increased by 29.9 percent. Harvest index was higher in 75-25 sesame/cowpea-cotton system. The assessment of cropping systems economic value showed that the highest economic value was related to cowpea-cotton which this is due to high yield of cowpea in monoculture (3772.4 kg.ha^-1) and higher yield of cotton (3406 kg.ha^-1) following cowpea and the lowest belonged to fallow-cotton system. Therefore, it was concluded that cowpea-cotton rotation increased the cotton productivity.