Two field experiments were carried out during 1998 and 1999 seasons at Beer Abou-Kalam Experimental Farm, Tour Sinai, South Sinai Governorate, Egypt.  The investigation aimed to study the effect of different irrigation intervals (3, 6, 12 and 15 days) with underground saline water (about 2800 ppm) and nitrogen fertilizer rates (0, 60, 90 and 120 kg N/fed.) on yield and its related characters as well as grain chemical composition of grain sorghum [Sorghum bicolor (L.) Moench] cultivar Giza-15. The following results were obtained :                 Prolonging irrigation intervals from 6 up to 15 days decreased significantly, at both seasons, 100-grain weight, grain and biological yields per feddan as well as the harvest index.  Such depressive effect was increasingly prominent with increasing the period of water withholding. A similar tendency could be noticed regarding total carbohydrate and crude protein contents in grain, leading to a reduction in the yield of each constituent per feddan.                 The present results have shown that yield and its components as well as the chemical composition of grains were significantly decreased by increasing N application rates to 90 and 120 kg N/fed. Due to the ineffective role of higher N doses in substituting for yield losses under water stress conditions, it could be concluded that medium nitrogen fertilizer rate (60 kg N/fed.) connected with a narrow irrigation intervals (i.e., irrigating every 3 days) are most favourable and economical for cultivating grain sorghum under the  saline conditions of South Sinai.