Abstract:A field trial was conducted at 2018/2019 & 2019/2020 at National Research Centre, Experimental Station, Nubaria district, Beheira Governorate, Egypt, to investigate L-phenylalanine (Ph) (50, 100 and 150 mg/l) external treatments role on Moringa oleifera L plant development, productivity and nutritional value (carbohydrates%, protein% and some macro element contents), antioxidant compounds (flavonoids and phenol), antioxidant activity (DPPH%) and amino acid composition under water deficiency (drought stress). Drought stress decreased markedly morphological characters of Moringa oleifera plant (shoot length, leaves number, plant fresh and dry weights), photosynthetic pigments, yield components and carbohydrates%, protein%, N, P, K, Ca and Mg contents with marked increases in phenol and Flavonoid contents as well as, DPPH%. Meanwhile, exogenous application with Ph were effective in improving plant growth criteria and various studied physiological aspects at normal irrigation or drought stress conditions. Moreover, Ph external treatment increased markedly and significantly yield and its components, carbohydrates, protein, nitrogen, phosphorous, potassium, calcium and magnesium contents. Also Ph treatments caused more increases in phenol, flavonoids contents and antioxidant activity under normal irrigation or drought stress. 100 mg/l was the most effective concentration on alleviating drought stress adverse effect on Moringa oleifera plants.