1. Captopril or SQ 14 225, administered orally twice a day, reduced the blood pressure of hypertensive patients whatever their clinical diagnosis and even when their plasma renin activity was ‘normal’ or low.
2. Long-term administration of captopril, either alone or together with diuretics, provides a powerful new tool with which to treat ambulatory hypertensive patients.
3. The renin system may play an important role in maintaining blood pressure in a majority of hypertensive patients.