In order to evaluation the effects of drought stress and nitrogen application on wheat yield and its components, a field experiment was organized in split split plot based on Randomized Complete Block Design with three replications at 2008-2010 in the research field of Karaj, Iran. Treatment included: two wheat cultivars (Gascogne and MV-17), three levels of nitrogen (0, 75 and 150 kg N ha -1 ), and three levels of withholding irrigation (I1: regular irrigation in total growth stages, I2: withholding irrigation at anthesis stage, and I3: withholding irrigation at seed filling period stage). Based on results, water deficit at anthesis time reduce seed number per spike and at seed filling period decrease seed weight. With nitrogen application, number of grain per spike increased 1.9% and 7.1% in 75 and 150 kg N ha-1 respectively. Withholding irrigation at anthesis caused that grain yield was declined from 8392.0 kg ha-1 to 7173.5 kg ha-1 compared with control treatment. Moreover, with 150 kg N ha -1 compared with check treatment, biological yield increased up to 28.0%. Also, harvest index was affected more by irrigation treatments than different levels of nitrogen application.