This study was conducted to examine DA-3002, a biosynthetic human growth hormone, for its acute and subacute toxicities in mice and rats. The drug was administered subcutaneously and orally at a dose level of 1.0, 3.0, 8.9, 26.7 or 80.0 lU/kg once for single dose toxicity and given subcutaneously at a dose level of 0.34, 1.7 or 8.4 lU/kg daily for 13 weeks to investigate repeated dose toxicity. In the acute toxicity study, doses up to 80 lU/kg had no adverse effect on the behavior or body weight gain. Pathological examinations revealed no abnormal changes which could be attributed to toxic effect of DA-3002. In the subacute toxicity study, the growth hormone was tolerated well in broth mice and rats. No drug related deaths occurred and all animals appeared to be normal throughout the dosing period. Increases in body weight gain, food utilisation and absolute organ weights were observed in the rats in the high dose group. Mild changes in the blood chemical parameters were also seen in the treated groups. Histopathologically, however, no abnormal changes were observed in any organ. The changes noted during the treatment periods presumably represent exaggerated pharmacological effects of the growth hormone, and no observed adverse effect level (NOAEL) was considered to be more than 8.4 lu/kg/day.