A multicenter, double-blind, placebo-controlled study of 310 elderly patients with mild-to-moderate essential hypertension was conducted in 20 sites throughout Europe, Brazil, and Israel to assess the antihypertensive efficacy, tolerability, safety, and dose-response characteristics of the novel calcium antagonist mibefradil in the elderly. Patients were randomly assigned to receive once-daily doses of 6.25, 12.5, 25, 50, or 100 mg of mibefradil or placebo for 4 weeks. Statistically significant and clinically relevant reductions in sitting diastolic blood pressure (SDBP) and sitting systolic blood pressure (SSBP) were observed with the 50 and 100 mg doses. Therapeutic responses reached 88.5% for SDBP and 76.5% for SSBP in the 100 mg group. Trough/peak ratios were > 75% in SDBP and SSBP with the 50 mg and 100 mg doses. At doses of 50 to 100 mg once daily, mibefradil was well tolerated and effective with a high antihypertensive response rate and consistent 24-hour blood pressure control in elderly patients.