This experiment was carried out with 12 Korean native heifers(8~12month old, body weight, 160~240kg) raised at a farm of Chang-Soo Livestock Cooperatives to evaluate the effects of rGH(recombinant growth hormone) on serum concentrations of growth hormone, estrogen, and IGF-I, weight gain, teat volume gain and processing enzyme activity of IGF-I, binding protein III at 28 day intervals. Animals used were injected with 250mg rGH at 14 day intervals from December to Ferbruary in 1994. The significant difference was found in the group of treatment on the 4th week in the endogenous GH(p<.01) and 8th week in estrogen and IGF-I(p<.05) after injectin of rGH in Korean native heifers. There were significant differences between control group and treatment group in weight and teat volume on 8th week after treatment(p<.05). Processing enzyme activity before injection of rGH were low. However, heifers injected with 250mg of rGH showed that processing enzyme activity of IGF binding protein was highly increased throughout the experiment. Present results suggest that injection of exogenous rGH to heifers can increase the growth performance and udder development of Korean native heifers by the endogenous hormonal changes.