The present investigation was conducted during 1997 and 1998 seasons to study the effect of potassium and phenylalanine foliar sprays on Pairi mango trees. The experimental results revealed that fruit yield, expressed as kg/tree or fruit number per tree, generally, increased as the levels of potassium increased. The best results in this respect were obtained by using 3% K₂O. In the meantime, results showed that phenylalanine did not affect the number of fruits per tree, but significantly increased the yield as kg per tree. In both years of study, peel total chlorophyll, generally, decreased, while carotene and anthocyanin increased by the foliar application of both K₂O and phenylalanine.                 Both potassium and phenylalanine foliar applications did not influence mango fruit firmness.                 Results also revealed that potassium and phenylalanine treatments caused an increase in reducing, non-reducing and total sugars on one hand, and reduction in starch on the other.                 Spraying Pairi mango trees with both potassium and phenylalanine increased total soluble solids and vitamin C. As for fruit acidity, potassium caused an increase in fruit juice acidity, while phenylalanine seemed not to affect fruit juice acidity.