Abstract: In order to study the effects of water stress and the application of brassinosteroide on growth and seed yield of Cowpea cv. Kamran, an experiment was carried out. The experiment was conducted in the form of split-plot at the basis of Randomized Complete Block Design (RCBD) with three replications. The main plots were comprised of 2 irrigation levels including irrigation after 60 mm evaporation from class A evaporation pan as normal condition (I0) and irrigation after 120 mm evaporation from class A evaporation pan as water stress conditions (I1). The sub plots were comprised of five level of application of brassinosteroide including the control (B0), seeds soaking in brassionsteroid 2 μM concentration (B1), seeds soaking in brassionsteroid 4 μM concentration (B3), spraying of brassinostroid 2 μM concentration (B4) and spraying of brassinostroid 4 μM concentration (B5). The results showed water stress increased SOD (113%), POD (54%), CAT (93%), GPX (24%) activities, MDA content (109%). In this study, water stress had no significant effect on APX activity. In the other hand exogenous brassinosteroid affected allstudied traits except POD activity. In the most studied traits spraying of brassinostroid with 2 μM concentration was more effective but in the case of seed yield seeds soaking in brassionsteroid with 4 μM concentration produced higher seed yield, although, it had not significant difference with spraying of brassinostroid with 2 μM concentration. The results of this study suggest that in order to mitigate the adverse effects of water stress in cowpea plants can be used the spray of brassinostroid with 2 μM concentration or seeds soaking in brassionsteroid with 4 μM concentration.