This trial examined 1350 sex-separated broilers at 24 days of age. Chicks were fed standard broiler starter diet for the first 21 days. Isocaloric grower diets (16.84%, 18.00% and 19.46% crude protein, respectively) were offered to broilers housed in sex-separated and mixed-sex pens from days 24 to 45 of the experimental period. While the body weights of sex-separated and mixed-sex broilers were similar, diet protein level and sex had a significant effect on the body weight of broilers during the experimental period (P < 0.01). Male broilers consumed more feed and had better feed conversion than females (P < 0.01). However, separate sex rearing had no significant effect on feed consumption or feed conversion rate (P > 0.05). As diet protein level decreased feed consumption increased numerically and feed conversion was negatively affected (P < 0.01). The percent rate of carcass yield, breast, thigh, abdominal fat pad, liver and gizzard was not affected by the diet protein treatment (P > 0.05), but females had heavier abdominal fat and gizzard than males (P < 0.01). Some slaughtering characteristics determined in the study were not affected by the broiler rearing methods. In conclusion rearing-sexes separately had no significant effect on the performance of broilers. Neither sex of broiler had tolerance to protein deficiency in the growing diets. Therefore the results do not support the idea of feeding male and female broilers diets nutritionally different based on protein level.