This investigation was carried out during the two consecutive seasons of 2004 and 2005 on mango trees (Mangifera indica L.) cv. Hendy Moloky grown in a private orchard at Belbeis district, Sharkia Governorate , Egypt to evaluate the effect of foliar spraying with vitamin C (Vit .C ) at 0.05 % [without spraying (control), spraying at beginning fruit set or spraying at 20 days after beginning fruit set], active dry yeast ( D. Y.) at 1 % [without spraying (control), spraying at beginning fruit set or spraying at 20 days after beginning fruit set] and their interactions onfruit quality and plant growth. Spraying with vitamin C at beginning fruit set or at 20 days after fruit set increased fruit weight and size as well as TSS % and Vit. C content in fruit juice. Peel weight was increased by spraying Vit. C at beginning fruit set, while fruit juice acidity was decreased under the effect of Vit. C spraying at 20 days after fruit set. All tested Vit. C treatments increased leaf fresh and dry weights as well as leaf tissue contents of chlorophyll a, chlorophyll b and total chlorophyll (a+b) as compared to the treatment without Vit.C. Dry yeast spraying applied at beginning fruit set increased fruit weight, size, and fruit juice content of Vit. C. When D.Y. applied at 20 days after fruit set, it increased leaf fresh and dry weight as well as leaf tissue contents of photosynthetic pigments. Peel weight and its ratio to pulp weight, TSS % and TSS/ acidity ratio in fruit juice were increased by D.Y. spraying at beginning fruit set or at 20 days after fruit set. As for interaction effects, the highest fruit weight and fruit peel weight were obtained when trees sprayed with D.Y. at fruit set x without Vit. C interaction. The combination treatment of Vit. C x D.Y applied at fruit set for each increased fruit size and fruit pulp weight. The uppermost values for chlorophyll a, chlorophyll b and total chlorophyll (a+b) in leaf tissues were recorded under treatment effect of spraying Vit. C at fruit set x spraying D.Y. at 20 days after fruit set. The all interaction treatments between Vit. C and D.Y. increased fruit juice content of vitamin C and TSS/ acidity ratio.