Two field experiments were carried out in the Experimental Station, Faculty of Agriculture, Mansoura University in the two summer seasons of 2014 and 2015 to study the effect irrigation water quantity and foliar application with salicylic acid on growth and yield of potato cv. Spunta grown under clay loamy soil conditions using drip irrigation system. The experiment layout was split plot in based on complete randomized block design with three replications. Quantity of irrigation water (700, 1000 and 1300 m³/ fed.) were present in the main plots, while foliar application with salicylic acid (0.0, 0.1, 0.2 and 0.3 g /litter.) were assigned in the sub plots. The results indicated that increasing water quantity up to1300 m³/ fed. led to a significant increase of vegetative growth parameters ( Plant height, leaves number, leaves area, number of main stem and foliage fresh weight per plant), leaves chemical composition (N, P, K, chlorophyll a, chlorophyll b and carotenoids), Tubers yield and its physical quality (tubers weight and number per plant, marketable and total yield), Tubers chemical quality ( Vit. C, TSS, N, P and K) and plant water relations (Relative water content). On contrary, foliage dry matter percentage, tuber dry matter percentage, hardness, density, electrolyte leakage and water use efficiency were decreased. With respect to the effect of foliar application of salicylic acid, the data exhibited that, the mentioned characters were increased compared to untreated plants except electrolyte leakage. The interaction between irrigation water quantity and spraying salicylic acid showed that the combination which consist of 1300 m³/ fed. and 0.2 g/l salicylic acid gave the highest values for most effective previous parameters.