Tow field experiments were carried out at a private Farm at Wadi El-Mollak, Abo-Hammad District, Sharkia Governorate, Egypt during 2006 and 2007 summer seasons. The aim of this work was to study the response of three maize hybrids i.e. single cross 18, three way cross 310 and three way cross 320 to N fertilizer levels (50, 75, 100 and 125 kg N/fad). A split-plot design with three replicates was followed, the three maize hybrids were arranged at random in the main plots whereas, nitrogen fertilizer levels were occupied the sub-plots. The obtained results of the combined analysis of the two growing seasons could be summarized as follows:                 Highly significant differences were detected among the three tested maize hybrids in most the growth and yield characteristics. SC18 maize hybrid surpassed the other two hybrids in grain yield/fad as a result of its superiority in yield components i.e. ear length, number of grains/row, number of grains/ear and 100-grain weight. TWC 310 plants were superior in plant and ear heights. Both TWC 310 and TWC 320 had the largest leaf area/plant. The plants of both SC18 and  TWC 320 gave the highest shelling percentage. The studied maize hybrids did not significantly differed in number of rows/ear.                 Each increment of N level up to 125 kg/fad resulted in a continuous and significant increase in plant height, leaf area/plant, ear length, number of grains/row, number of grains/ear, shelling percentage and grain yield/fad. Ear height, number of rows/ear and 100-grain weight were gradually increased with increasing N level up to 100 kg N/fad.                 The interaction between the two studied factors significantly affected leaf area/plant and grain yield/fad. Planting TWC 320 with application of 125 kg N/fad is the best to obtain the largest leaf area/plant whereas, planting SC18 with 100 or 125 kg N/fad is the best to obtain the highest grain yield/fad.                 Positive and significant correlation coefficients between maize grain yield on one hand and each ear length, number of grains/row and number of grains/ear on the other hand were observed, while positive and insignificant correlations were found between grain yield and other studied characters. The direct effect of ear length was 49.5% being higher than those of number of grains/ear and 100-grain weight which were 2.85 and 4.40% of grain yield variation, respectively.