Field trials were conducted during 1991 and 1992 seasons, at the Agricultural Research and Experiment Center. Faculty of Agriculture. Moshlohor. Zagazig University to evaluate the effect of different N levels (15. 30. 45. 60. 75, 90 and 105 kg N/fed.) and nitrapyrin as a nitrification inhibitor on growth and yield of maize. Results showed thai growth. yield and yield components as well as protein content in grains of maize were significantly increased by increasing N rates up to 105 kg N/fed. Addition of nitrapyrin with urea produced the highest values of growth. yield and yield components of maize. Using nitrapvnn with urea, increased maize grain yield/fed, by 12.6 and 10.3% In 1991 and 1992 seasons. respectively, as compared with urea alone. Plant height in 1991 and 100-kernel weight. shelling percentage. grain yield/fed, and protein content in grain in the two seasons were significantly influenced by the interaction between N levels and nitrapvrin. Maize grain was significantly increased ith increasing N levels up to ،05 kg N/fed, when nitrapvrine sas not used. However, combination of nitrap rin with urca significantly increased grain yield of maize with increasing N levels up to 75 kg N/fed tinder the conditions of this sIud it can he concluded that using nitraj, rin as iiilnflcalion inhibitor combined wit Ii 7i kg N/fed (urea) produced t lic highest grain ield of malie and sa cd 411 kg N/hod