To find out the optimum timing of N application on seed cotton yield, two years field experiment was conducted at Adaptive research Farm Sargodha, Pakistan during summer seasons of year 2011 and 2012. Cotton variety MNH 886 was sown. Five treatments were applied as full nitrogen at first irrigation, ½ nitrogen at first irrigation + ½ nitrogen at 2nd irrigation, ½ nitrogen at sowing + ½ nitrogen with 2nd irrigation, ½ nitrogen at sowing + ½ nitrogen at flowering stage, ten split applications of N with each irrigation. Randomized complete block design was used for layout using three replications. Significantly the highest seed cotton yields (1559 kg ha-1 and 1135.7 kg ha-1 during years 2011 and 2012, respectively) were observed with ten split applications of N with each irrigation. The maximum seed cotton yield in response to split N application seems due to the highest number of bolls plant-1 and boll weight in that treatment. Regression analysis also showed the significant strong positive relationship of seed cotton yield with number of boll plant-1 (R2=0.867) and boll weight (R2=0.895).