Résumé : We evaluated the efficacy and tolerance of a single daily dose of quinapril in 10 patients with mild to moderate arterial hypertension. Patients were treated for 12 weeks after a 2-week placebo run-in period. 24-hour monitoring of arterial pressure was performed the day before inclusion and after treatment for 12 weeks. Standing and sitting blood pressures were measured at the end of the 4th, 8th and 12th weeks. Pressures recorded during 24-hour monitoring showed a significant reduction of systolic, diastolic and mean arterial pressures. A significant decrease in blood pressure was seen after 4 weeks' treatment and persisted until the end of the trial. Heart rate remained unchanged throughout the study. Biological parameters did not change. No adverse effects were reported and there were no changes in laboratory tests. Tolerance may be considered excellent.