Nitrogen is one of the most important nutrients required by plants for vegetative growth and development. To investigate the effect of different levels of nitrogen on growth as well as grain yield of spring planted maize under irrigated conditions of central Punjab, a field trial was executed at Research Area of Maize and Millet Research Institute, Yousafwala Sahiwal, Punjab Pakistan, during 2009. The experimental design was randomized complete block design (RCBD) which was replicated thrice. Maize (cv. Sadaf) was sown in 75 cm apart rows, while plant to plant distance was maintained at 20 cm. Five levels of nitrogen (100, 120, 140, 160 and 180 kg per hectare) were employed as experimental treatments. Results revealed that all levels of nitrogen influenced the yield components as well as grain yield of maize. The highest grain yield (6.93 t ha-1) and biological yield (12.91 t ha-1) was given by nitrogen applied at the rate of 180 kg/ha. Similarly, the maximum number of grains per cob (471.3) and 1000-grain yield (328.4 g) was given by 180 kg/ha of nitrogen. The plant height, number of leaves per plant and stem diameter were also increased with increased level of applied nitrogen. Thus higher doses of nitrogen have the potential to give comparatively higher grain yield of spring planted irrigated maize.