1. We have treated 25 patients with renovascular hypertension with balloon catheter dilatation. 2. In 17 patients, surgical treatment was thought to be either risky or difficult due to the presence of a serious medical condition or because of the peripheral location of the lesion. 3. Seventeen patients had atherosclerotic lesions, six patients had fibromuscular dysplasia and one patient had neurofibromatosis and one had stricture of an aorto-renal bypass graft. 4. Of the total group, six in the atherosclerotic group, three patients with fibromuscular dysplasia and the one with neurofibromatosis are normotensive without medications. 5. Five patients with atherosclerosis, two patients with fibromuscular dysplasia and the patient with aorto-renal bypass graft are either normotensive or have reasonable control of blood pressure with medication. 6. Four technical and treatment failures and three major medical complications were encountered. Recurrence of stenosis occurred in eight patients but none of these was in the fibromuscular dysplasia group.