The efficacy and tolerability of lisinopril and sustained release (SR) verapamil hydrochloride were compared in 68 patients (mean age, 60 years) with mild to moderate uncomplicated essential hypertension. The goal of therapy was to achieve and maintain a supine diastolic blood pressure (SDBP) of less than 90 mmHg or a fall in SDBP greater than or equal to 10 mmHg. Patients received lisinopril (10 to 40 mg QD) or verapamil SR (120 to 480 mg QD) during a variable titration period (two to eight weeks) to achieve goal blood pressure prior to a four-week maintenance treatment period. Among the 62 patients who completed the titration period, the mean baseline supine systolic/diastolic blood pressures were 155/97 mmHg for the lisinopril group and 150/95 mmHg for the verapamil SR group. Ninety-seven percent of patients in the lisinopril group and 100% of patients in the verapamil SR group achieved SDBP control at the end of titration therapy. At the end of the maintenance treatment period, 82% of the lisinopril-treated patients and 81% of the verapamil SR-treated patients had SDBP control. Mean decreases in SDBP from baseline were comparable for both treatment groups. At the end of titration, mean decreases were 11.3 mmHg for the lisinopril group and 10.7 mmHg for the verapamil SR group; at the end of maintenance treatment, mean decreases were 10.5 mmHg and 8.5 mmHg. Thus both drugs were equally effective in older patients with mild to moderate essential hypertension. Both drugs were generally well tolerated. One patient in the lisinopril group and four patients in the verapamil SR group experienced adverse effects that required withdrawal from the study.