Two field experiments were carried out at Sids Agricultural Research Station, Eleni-Swef Governorate in the seasons of 2003 and 2004. The aims of this investigation were to study the effect of nitrogen levels (0, 80, 120 and 160 Kg Nifed) on grain yield (ard!fed)of Single Cross 10 (SC 10) and to determine the response degree of grain yield to N fertilizer as well as to estimate the economic optimum N rate. Also to investigate the relationship between grain yield and its components using some statistical techniques namely: correlation, stepwise multiple linear regression and path-coefficient. The highest grain yield (ardifed) of the tested cultivar was produoed by supplying 160 Kg Nifed in the two seasons. Quadratic model was the best of the tested models for describing the relationship between grain yield of maize hybrid to N   fertilizer.   The economic optimum N rate (121.3 and 120.8 Kg Nifed), respectively, for the two seasons (2003 and 2004). Grain yield produced by adding optimum N rate (26.8 and 2B ardifed) respectively and net return E.E 1106.8ifed in the first season (2003) and E.E1250.Bifed in the second season (2004). The results of statistical analysis techniques indicated that ear height, plant height, and ear length were the most important contributing variables in the total variability of maize grain yield. These variables have to be ranked the first in breeding program for improving maize grain yield.