Subacute toxicity and recovery tests of labetalol hydrochloride, alpha- and beta-adrenoceptor blocking agent, were carried out using male and female Wistar strain rats. The drug was orally administered at 50, 150, 450 or 1000 mg/kg/day for 1 month. In all the drug-treated groups, increase in salivation was observed from immediately to 15 minutes after dosing through the treatment period. Eight of the 10 males and 9 of the 10 females in the group treated with 1000 mg/kg/day died of intoxication. Suppression of body weight gain was observed in male rats in the 450 and 1000 mg/kg/day groups and in female rats in the 1000 mg/kg/day group. In the 150 mg/kg/day and higher dose groups, water consumption showed a tendency to increase as compared with that of control group. Increase in urine volume was observed in female rats in the 450 mg/kg/day group. In the serum biochemical examination, slight elevation in potassium levels was noted in the 150 and 450 mg/kg/day groups. In histopathological findings, some abnormalities were found in the groups treated at 150 mg/kg/day and higher. Major abnormalities found in organs were; congestion and hypremia of various organs due to vasodilation, swelling of parenchymatous cells in liver and kidneys, and loose arrangement and change in the thickness of muscle fibers in cardiac and skeletal muscles. None of these abnormal findings was found in any examination in recovery tests.