This study was conducted throughout two seasons on grafted Ewais and Sidik mango trees grown at Elwadi El-Faregh Cairo/Alexandria desert road, Giza governorate Egypt. Trees were treated at the first week of October 2001 and 2002with potassium nitrate (KNO3) at 1, 2 and 4% as a foliar spray, while Paclobutrazol (PBZ) was added at the first week of October 2001 at 2.5, 5 and 7.5 g per tree as a soil drench in 20 liter of water. Results indicated that both PBZ and KNO3 increased total soluble sugars in leaves compared to the control. A direct relationship was found between the used concentration and total sugars content. The highest total sugars content was recorded in Dec. then decreased gradually during Jan. and Feb. after that another increase occurred in Mar. PBZ and KNO3 significantly improved amino acids content in leaves of both cultivars. Increasing the used concentration of both chemicals significantly increased this content. Total amino acids increased from Nov. to Dec. then it decreased significantly during the period from Jan. to Mar. This was confirmed in both cultivars during the two seasons.