1 This was a multicentre, double-blind, parallel study in 216 patients with mild to moderate (supine diastolic blood pressure = 95-115 mm Hg) essential hypertension. 2 After a 4-week placebo washout, patients were randomized to placebo or lisinopril 1.25, 5, 20 or 80 mg once daily for 6 consecutive weeks. Supine and erect blood pressure was measured 24 h postdose at the end of weeks -2, 0, 2, 4, and 6. 3 There was a linear dose-response relationship for both supine and erect blood pressure. Diastolic blood pressure reductions in the lisinopril 20 and 80 mg day-' groups were significantly greater than in the placebo or lisinopril 1.25 and 5 mg day-' groups. 4 Lisinopril, at doses up to 80 mg day-', was well tolerated.