One thousand and five hundreds feather sexed day-old chicks (Cobb 500) were divided into three equal groups; males, females and straight- run (as hatched). The 3 groups were reared identi-cally. Body weight was significantly higher in male group compared with either female or straight-run groups. Also, the feed conversion ra-lio of the male group was significantly lower than the female group. The litter of the male group showed significantly lower moisture content as compared with the female group. No significant differences were observed in the maternal anti-bodies (for both ND and IBD viruses) between separately grown males and females. However, the non-specific immune response to SRBCs was significantly higher in females than males.