Two cases of primary intimal fibroplasia of the renal artery with renovascular hypertension are described. Case 1 was 27 year old female who was incidentally found to have blood pressure of 210/130 mmHg on routine physical examination. Renal arteriogram revealed tubular narrowing of the mid protion of the left renal artery. Both patients showed lateralization in renin activity at the involved side renal vein. Case 2 was a 10 year old girl who was first noted to have a hypertension of 180/120mmHg after a sudden attack of seizure, vomiting and altered consciousness. Renal arteriogram showed concentric narrowing of the proximal half of the right renal artery. Histopathologic examination of the affected arterial segments from both cases showed essentially same findings, i,e., diffuse fibrous thickening of the intima occluding the lumen, focal fragmentation, duplication and disappearance of the internal elastic membranes. There were no deposit of lipid and inflammatory cells. The media and adventitia remained intact. The blood pressure of both patients became normal, after the surgery and the patients are in good health up to this time.