Abstract In an open, multicenter, randomized clinical study, the antihypertensive efficacy and tolerability of nicardipine slow release (SR) and enalapril were evaluated in 561 patients aged 60 years and older with mild to moderate essential hypertension. After a 2- to 3-week washout period, the patients were randomly assigned to receive nicardipine SR 40 mg twice daily or enalapril 20 mg once daily for 6 months. After 2 months of treatment, if the patient's blood pressure remained elevated, hydrochlorothiazide (HCTZ) 12.5 to 25 mg/day was added to the monotherapy. The results of this study confirmed the antihypertensive efficacy and tolerability of nicardipine SR and enalapril when given as monotherapy or in combination with HCTZ. However, in the nicardipine group, the number of responders to monotherapy and the degree of reduction in systolic and diastolic blood pressures during monotherapy was greater than that in the enalapril group. Thus the need for combined therapy was lower in the nicardipine group. Heart rate did not change significantly in either group. The incidence of side effects was higher in the nicardipine group (ankle edema, headache, facial flushing, and palpitations) when compared with the enalapril group (fatigue, cough, taste disturbance, and dizziness), but the number of drug-related withdrawals was significantly higher in the enalapril group, mainly because of cough. These results support the hypothesis that the antihypertensive efficacy of calcium antagonists is age dependent and related to pretreatment blood pressure values. Thus dihydropyridine calcium antagonists, such as nicardipine SR, appear to be particularly effective and well tolerated in the treatment of elderly hypertensive patients.