two experiments were carried out to determine the nutritional requirement of total lysine for ross broiler chickens from one to 21 and 22 to 40 days of age, of both sexes. the parameters evaluated were weight gain, feed intake, feed conversion and carcass evaluation. in each experiment, a completely randomized experimental design, in a 2 x 6 (two sexes and six dietary lysine levels) factorial arrangement with six replicates, using a total of 1440 birds, was used. the basal diets with 1.03% total lysine, 22.0% cp and 3000 kcal me/kg in the first experiment and 0.92% total lysine, 20.0% cp and 3150 kcal me/kg in the second experiment, suplemented with six levels pure lysine (0.0; 0.06; 0.12; 0.18; 0.24 and 0.30%), were used. considering weigth gain and feed conversion, the dietary requirement estimates for the experiment from 1 to 21 days were 1.303 and 1.249% total lysine and 1.183 and 1.129% digestible lysine for males and females, respectively. for the experiment from 22 to 40 days, the performance and evaluation carcass values were 1.164 and 1.143% total lysine and 1.044 and 1.023% digestible lysine for males and females, respectively.