<p>The objective of this study was to evaluate the protective impacts of exogenously applied nitric oxide (NO) in soybean plants grown under drought stress. Four PEG concentrations (0, 5, 10 and 15%) and one NO concentration (100 μM) were applied to soybean plants. NO application removed the injurious effects of drought stress on plant growth and enhanced the growth at all levels of drought. No treatment decreased drought-induced oxidative injuries by increasing the contents of flavonoids and anthocyanins. NO caused osmotic regulation in stressed plants by enhancing the soluble sugar content. NO application increased aconitase, fumarase and succinate dehydrogenase activities, thereby enhancing respiration. The enhancement of growth by NO can be explained by increased DPPH (1, 1-diphenyl-2-picrylhydrazyl), nitrate reductase activity and chlorophyll and protochlorophyllide content. NO treatment enhanced stress tolerance in soybean plants by increasing the levels of indole-3-acetic acid and gibberellic acid, as well as the contents of Ca²⁺, K⁺ and P. In conclusion, the exogenous application of NO improved the performance of soybean plants under drought stress, suggesting a multipurpose role for NO in diminishing the negative effects of drought.</p>