Leaf area index (LAI) and total dry matter are important growth and yield-determining factors in maize (Zea mays L.). Field experiment was conducted to investigate the impact of different N-fertilizer sources [urea, calcium ammonium nitrate (CAN) and ammonium sulphate (AS)] and rates (50, 100, 150 and 200 kg ha-1) on mean single leaf area (MSLA), number of leaves plant-1 (NLPP), LAI and total dry matter (TDM) of maize genotypes “Local cultivars (Azam and Jalal) vs. hybrid (Pioneer-3025)”. The experiment was conducted at the Agriculture Research Farm of The University of Agriculture Peshawar during summer 2008-10. The results indicated that all the experimental plots treated with N produced higher MSLA, NLPP, LAI and TDM than control (N not applied). The MSLA, NLPP, LAI and TDM increased with higher N rates (150 and 200 kg N ha1). Application of CAN and AS produced higher MSLA, NLPP, LAI and TDM than urea in the 1st year, but no significant differences were observed in the 2nd year. The hybrid (P-3025) produced higher MSLA, NLPP, LAI and TDM than Azam and Jalal. The increase in MSLA and NLPP showed positive relationship with LAI. The TDM increased with increase in LAI. Application of N either as CAN or AS at the rate of 200 kg ha-1 was recommended for the high yielding hybrid maize but 150 kg N ha-1 was most suitable for the low yielding local cultivars in the study area