The purpose of this study was to test tolerance and the antihypertensive effect of nicardipine, a new calcium antagonist, in 31 elderly patients aged 57-95 years. The study was conducted as a double-blind trial. The patients were allocated randomly to either active or placebo treatment. Sixteen patients were given 10-30 mg of nicardipine three times a day (mean dose, 69.4 mg per day); 15 other patients received a matching placebo. After 4 weeks, nicardipine lowered mean blood pressure, and the changes in systolic and diastolic blood pressure were significantly greater in the nicardipine group than in the placebo group. Nicardipine was tolerated very well, and orthostatic hypotension was never observed. There was no change in heart rate. Plasma renin activity (PRA) was measured in eight patients. There was no correlation between PRA and the antihypertensive effect of nicardipine. A pharmacokinetic study performed in 15 elderly patients showed a fast rate of absorption and also higher plasma levels than those observed in hypertensive adults (mean age, 54 years). This trial demonstrates the effectiveness of nicardipine in elderly hypertensive patients.