This study was conducted to determine the growth performance and carcass characteristics of fattening Hanwoo heifers slaughtered at different ages. Twenty one Hanwoo heifers were randomly allocated to three groups (32, 36 and 40 months age), with 7 steers each, respectively. In the result, initial and final body weights were 125.6 and 651.0 kg, respectively. Average daily gain was significantly low at final stage compared with other growth stages (p<0.05). Dry matter intake was the peak at the intermediate fattening stage (p<0.05). The feed conversion ratio was significantly lower at growing stage compared to other stages (p<0.05). In yield traits, carcass weight was greater in 40 months age group compared to other groups (p<0.05). Yield index was greater in 32 months group compared to 40 months of age (p<0.05). Marbling score, meat color, fat color, texture, and maturity were not different among groups (p>0.05). However, marbling score tended to be increased in 40 months age group (5.9) compared to other groups. The appearance rate (%) of meat quality grade more than 1+ was greater at 40 months old group than other groups.