An experiment was conducted in randomized complete block design with four replicates to study the effect of spraying nitrogen fertilizer as a urea with concentration 0 , 10 , 20 , 30 mg/liter on the characters of cotton Koker 310 at summer season 2007 in experiment station of cotton research unit in mosul technical institute , all the agricultural practices were done for the end of season where study the plant height , number of nodes to the first fruit branch , number of vegetative branches , number of fruiting branches , number of bolls /plant , boll weight , seed index , lint index , lint percentage and seed cotton yield kg/h . Spraying urea fertilizer in concentration 20 mg/liter significantly exceeded from control in plant height , number of fruiting branches , number of bolls/plant , boll weight and seed cotton yield kg/h in percent 63.72 , 24.49 , 43.92 , 8.92 , 42.59% respectively while seed index significantly differed from control treatment in other used concentrations . Spraying urea fertilizer reflected significantly linear regression correlation to increase seed index and degrease lint percentage in addition to positive significant correlation for seed cotton yield with plant height , number of vegetative branches , number of fruiting branches , number of bolls /plant , boll weight and seed index .