A field experiment was conducted with Valancia orange and Balady mandarin trees grew in clay loam soil at Orchard Sids Horticultural Research Station, Beni Suef Governorate, Egypt, for two consecutive seasons (2008 and 2009) to investigate the effects of foliar application of potassium thiosulphate (KTS) and ammonium polyphosphate (APP) on yield, leaf mineral content, external quality and Juice quality of Valencia orange and Balady mandarin. The obtained results indicated that KP4 (spraying 1% two times) treatment gave the highest weight, number of fruit and yield for each cultivars in the two seasons. All treatments significantly increased volume and diameter of fruits comparing to control. On the other hand rind thickness decreased significantly with different spray treatments .Increasing the rate and number of foliar application of KTS and APP increased TSS and TSS/acid ratio and decreased juice acidity . All treatments significantly increased N,P and K in the leaves of both cultivars comparing with the control .Different treatments significantly increased juice percent. As regards to cultivar,Valencia was better than Balady mandarin in all treatments in both seasons.Valencia cultivar gave the highest value of vitamin C compared with Balady mandarin under all spray treatments