A 36-year-old male was evaluated for treatment-resistant hypertension. A high platelet count 828 x 10(9).l-1, led to the diagnosis of essential thrombocythemia (ET). Aorto-renal angiography revealed critical bilateral renal artery stenosis and coronary angiography showed three-vessel disease. Percutaneous transluminal renal angioplasty was only partially successful. The patient received a 12-week course of busulphan and subsequently the thrombocyte count decreased to 200 x 10(9).l-1. Renal angiography 12 months later showed bilateral regression of the renal artery stenosis with lowering of the blood pressure to normal levels.