SummaryCaptopril in association with furosemide was used to treat seven patients with intractable severe hypertension. All patients were unresponsive (dias tolic blood pressure higher than 105 mm Hg) to tritherapy (diuretic, betablocker, and vasodilator). An important fall in blood pressure was observed in all cases, and in four patients permitted a complete control of blood pressure, with only low doses (less than 300 mg/day) of the drug. This good effect was already present after one month of treatment, and persisted unchanged for as long as 18 to 26 months. Plasma renin activity increased and remained elevated after one year of treatment.Side effects were encountered in four patients: skin rashes in one, moderate taste disturbance in two, and one episode of orthostatic hypotension Which disappeared with furosemide withdrawal. None of these side effects caused the interruption of captopril. The careful follow-up of serum creatinine and creatinine clearance during one year of therapy in the seven patients confirms that a long-term blood pressure reduction by captopril in severe hypertensives with altered renal function may be obtained without further decrease of the glomerular filtration.