Twenty-six patients were selected for treatment with minoxidil on the basis of hypertension which could not be controlled either because of (1) drug failures and/or (2) side effects of drugs. Sixteen out of the 26 had had one or more previous episodes of malignant hypertension. Reduced renal function was present in the majority; eight patients were on dialysis. Average preminoxidil blood pressure was 202/127 mm. Hg supine and 162/106 upright which fell to 154/87 supine and 143/86 upright after minoxidil. Propranolol or methyldopa was given to control the reflex increase in heart rate. Edema and congestive heart failure refractory to large doses of potent diuretics necessitated discontinuation of the drug in two patients. Minoxidil proved highly efficacious regardless of initial level of blood pressure, etiology, or supine or upright posture.