A field experiment was conducted on a special farm near kafr El-sheikh, kafr El-sheikh governorate, during the winter season 2012 / 2013 to investigate the effect of urea fertilizer levels in the presence or absence of urease inhibitor thiophosphoric triamide (NBPT) on wheat plant. Six treatments were arranged in a split-block design, which were the simple possible combination between three levels of urea fertilizer i.e.50, 75 and 100kg N/fed for wheat plant as main plots and two treatments of (NBTP) (0 and 4% from the N-level), each treatment was replicated three times. Results indicated that; the average values of growth parameters, yield and its components and chemical composition of wheat plant were significantly increased as the level of N-fertilization was increased either in the presence or absence of urease inhibitor, but the rate of increases for the plants treated with (NBTP) were more than that obtained from the untreated plants. On the contrary of this trend, adding of N-levels in single form significantly increase the average values of nitrate and nitrite contents in wheat plant as the level of N-fertilization was increased while, such effect was sharply and significantly decreased due to an adding of (NBTP) in combination with the same levels of N-fertilization. The most suitable treatment which realized the highest yield of grain of wheat plant was connected with the plants treated with 100 kg N/fed combined with urease inhibitor.