A FIELD experiment was conducted in farmer's field located at Gammsa district, Dakahlya Governorate, Egypt, during two successive winter seasons 2017 and 2018 to determine and evaluate the response of watermelon grown on sandy soil to three irrigation regimes; 100%(I 1), 85%(I 2) and 70%(I 3) of soil field capacity and four applications of bio-mineral fertilizers; F 1 Applying the recommended dose of NPK (100%RNPK), F 2 (85%RNPK + biofertale), F 3 (70%RNPK + rhizobacterien) and F 4 (55% RNPK+ mixture of biofertale + rhizobacterien). Results showed that both of irrigation and fertilization treatments had highly significant effect on yield and its components of watermelon plants in both seasons. Maximum fruit yield and its components were achieved with I 2 and F 3 treatments in both seasons. Irrigation with (I 2), led to increase fruit yield by (14.26 and 14.30%) compared with I 1 and the corresponding values (11.72 and 12.97%) with (F 3) compared with F 1 in 1 st and 2 nd seasons, respectively. I 3 achieved higher values of TSS, vitamin C, soluble sugar, PIW and water saving. Moreover, F 3 followed by F 4 produced the highest value of PIW in both seasons compared with F 1. The combination of I 2 F 3 has superiority in increasing fruit yield and its quality, net return and economic efficiency. Net return from water unit was resulted from the combination of (I 3 F 4) and (I 3 F 3) as compared with (I 1 F 1) in both seasons, respectively.Generally, it could be concluded that I 2 F 3 or I 2 F 4 is the most efficient treatment for achieving economical watermelon fruit yield, economic return and saving water and mineral fertilizers.