This study was conducted to compare among bull, steer and heifer on growth performance, blood composition and carcass traits according to fattening phase in Hanwoo. 12 month of aged 4 bulls (339.8±18.5 kg), 4 steers (309.8±13.2 kg), and 3 heifers (290.0±16.7 kg) were allocated in the stalls with individual feeding system during 20 months. Average daily gain was not different among the treatment groups during early fattening phase, but higher in the bulls and lower in the heifers after mid-fattening phase (p<0.05). The difference of body size by animal groups appeared from 24 month of age, and wither height and body length of Hanwoo heifer were the smallest (p<0.05) among treatment group. But wither height was not difference among treatment groups at 32 month of age. At 12 month of age, concentrations of serum cholesterol, triglyceride, glucose and total protein were higher in the heifers compared to other groups, and serum GPT (Glutamic pyruvic transaminase) was the highest (p<0.05) in the bulls, and serum GOT (Glutamic oxaloacetic transaminase) was the highest (p<0.05) at late fattening phase in the bulls. Meat yield index was similar between the bulls and the heifers, and the lowest (p<0.05) in the steers. Marbling score was significantly higher (p<0.05) in the steers and the heifers than in the bulls, and meat quality was the best in the steers among treatment groups. The results of this experiment might be used as a basal data on difference between gender in revision of Korean feeding standard for Hanwoo.