SummaryTwenty-five severe hypertensive patients uncontrolable with conventional medication either because of resistance or because of dose limiting sideeffects received minoxidil, a powerful new vasodilator, for a total period of 300 months (1 to 36 months-mean duration: 12 months).Mean daily dosage varied from 15 mg during the first month (25 patients) to 47 mg at the 18th month (7 patients). Compared with initial values measured under conventional treatment (230/130), systolic and diastolic blood pressures dropped 20 % during the first month (180/100) and more than 40% at 18 months (130/80). During the following months these good results were maintaind with similar doses of minoxidil.Increased heart rate and cardiac output, hyperreninemia and fluid retention are usual physiological consequences of vasodilators. Therefore, betaadrenergic blocking agents and diuretics, sometimes in very large doses, have to be used with minoxidil.Hirsutism is a frequent side effect. It represents a serious limitation to the use of the drug in females and led to a drop-out of 5 of them.