Two field experiments were carried out at Etay El– Baroud Agricultural Research Station, El- Beheira Governorate during 2013/ 2014 and 2014/2015 seasons to study the effect of three nitrogen sources (Urea, Ammonium sulphate and Ammonium nitrate) and four different levels of nitrogen fertilization (0, 50, 75 and 100 kg N/fed) on some physiological characters, yield and yield components of wheat. Results indicated that days to heading was significantly affected by N sources in the second season only. While, days to maturity and plant height were insignificantly affected by N sources in the two seasons. Whereas, days to heading, days to maturity and plant height were significantly increased by increasing nitrogen levels from 0 up to 100 kg N/fed in the two seasons. Number of spikes/m², number of grains/spike, grain weight /spike and 1000- grain weight were gradually and significantly influenced by nitrogen sources in the first and second seasons. The highest number of spikes/m² and number of grain/spike were obtained when nitrogen fertilizer added as urea while lowest values obtained when nitrogen fertilizer added as Ammonium sulphate during the two seasons. Whereas, 1000- grain weight recorded the highest value at Ammonium nitrate and the lowest at Urea, On the other hand, spike length and number of spikes/m² were insignificantly influenced by nitrogen sources in both seasons. All above parameters: were significantly increased by increasing nitrogen levels from zero to 100 kg N /fed during the two studied seasons. The highest values obtained at 100 kg N/fed while, the lowest ones were obtained under control. Grain, straw and biological yields were significantly influenced by N. sources in the two studied seasons. Urea as sources of N surpassed on the others sources under study for all studied characters. On the other side, harvest index (%) was significantly affected by N sources in the second season only. All other studied parameters were significantly increased by increasing N levels from zero to 100 kg N/fed in the two seasons. The heaviest grain, straw and biological yields were given at 100 kg N/fed while, the lightest at control in the 1^st and 2^nd seasons. It is important to clear that, the highest value of harvest index (%) was taken at 75 kg N/fed and the lowest at control treatment (zero N). The interaction between nitrogen sources and N levels significantly affected, plant height, number of spikes /m², grain weight/spike and 1000- grains weight. The highest numbers were taken at 100 kg N/fed of Urea during the first and the second seasons. Each of straw and biological yield was insignificantly affected by the interaction between nitrogen sources and nitrogen levels in the two studied seasons.