This case report deals with an eight-year duration severe high renin hypertension and its consequences. In 1975, a 13 years old girl was found to have blood pressure (BP) levels of 240/150 mmHg with bilateral papilloedema. Hypokalemic alkalosis, a 45 mm Sokolow index (SI) and very high peripheral renin activity (PRA) were also noticed. Renal vein renin sampling (RVRS) suggested secretion from the left kidney but intravenous pyelography and renal arteriography were normal. BP levels were first controlled by triple treatment but rose one year later, despite adjunction of beta-blockers. High PRA was again found, but without hormonal gradient on a second RVRS. From 1977 to 1982, BP never fell to normal levels despite quadruple treatment. In 1982, a stage II optic fundus, a 58 mm SI and 2 g/day proteinuria are noticed, so that a new complete etiologic work up is undertaken in 1983: PRA is still high, with a dramatic acute BP fall after captopril and no gradient on a third RVRS, but intravenous pyelography, tomodensitometry and selective arteriography disclose a 4 cm diameter poorly vascularized tumour on the surface of the lower pole of the right kidney. BP levels are controlled for three months by captopril + chlorothiazide. The tumour is removed in january 1984. RVRS by direct peroperative punction indicates (a posteriori) hormonal secretion from the right kidney lower pole. Histologic examination and immunofluorescence with antirenin serum corroborate the juxtaglomerular origin of the tumour. Eighteen months later, BP is permanently normal, SI is 30 mm, and there is no proteinuria.(ABSTRACT TRUNCATED AT 250 WORDS)