WATER stress is one of the most important abiotic stresses that …….....may limit agriculture production worldwide. This work was carried out on mango trees (Mangifera indica L.) to study the effect of exposure to different levels of drought stress (65, 75, 85 and 100 % of full irrigation requirements), in addition, to evaluating the role of using some plant growth promoting rhizobacteria (PGRP); such as Azospirillum and Azotobacter, in alleviating drought-induced changes. Physiological and biochemical changes were determined in mango leaves after two seasons of different treatments. Results indicated that membrane stability, photosynthetic pigments and insoluble sugar contents were significantly decreased with increasing drought levels, while electrolyte leakage, soluble sugars, total carbohydrates and proline content were sharply increased compared to control. Lipid peroxidation level and the activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) enzymes showed progressive increases with drought levels. Application of biofertilizers may be effective in alleviating the adverse effect of water stress. Bio-fertilizers caused marked increase in photosynthetic pigments and carbohydrate contents and a decrease in proline content compared to control.