AIM: To compare the therapeutic effects and adverse reactions of nicardipine and labetalol injection in treating acute and severe hypertensions. 　METHODS: Sixty-seven patients in nicardipine group (M 46, F 21; age 52 a± s 11 a) were given nicardipine 2 mg in 0.9 % sodium chloride or 5 % glucose injection 10 mL within 2 min iv, first, and then given 30 mg nicardipine in 0.9 % sodium chlocide or 5 % glucose injection 250 mL by continual intravenous infusion for 6 h. Sixty-one patients in labetalol group (M 41, F 20; age 53 a±9 a) received 50 mg labetalol in 5 % glucose injection 20 mL by intravenous once. The treatment could be repeated every 15 min, in case it was less effective, but the total dose should be no more than 200 mg.　RESULTS: The treatment for the nicardipine group and the labetalol group, reached the marked effect within 5 min. The total marked effective rate was all 100 % (P>0.05). Severe adverse reactions occured in the two patients (one occured significantly lowering of blood pressure, and the other aggravated asthma) in the labetalol group. 　CONCLUSION: Intravenous nicardipine and labetalol are fast and smooth in reducing the blood pressure of the patients with acute and severe hypertension, but the safety of nicardipine is superior to that of labetalol