92 patients with fibromuscular hyperplasia (FMH) seen at the University Hospital Zurich were studied. Renovascular FMH was the most frequent manifestation of the disease (89%). FMH of the cerebral arteries was seen in 26%. The intestinal and subclavian arteries were involved in 9% each and the iliac arteries in 5% of the patients. In 2 patients each FMH of the abdominal aorta or the coronary arteries, respectively, was found. 26% of the patients had systemic disease with involvement of 2 or more arteries. Half of the patients with bilateral renovascular disease showed additional extrarenal FMH. All patients with renovascular FMH were hypertensive (mean blood pressure 194 +/- 34/119 +/- 18 mm Hg). Surgery, percutaneous transluminal angioplasty (PTA) and medical therapy were equally effective in controlling blood pressure. The cure rates were 52% in patients undergoing surgery and 50% in those treated with PTA. The complication rate, however, was higher with surgery (11%) than with PTA (3%). 62% of the patients treated medically were normotensive. Major side effects occurred in 4.8%. The outcome of curative interventions (surgery or PTA) was influenced by the extension of FMH. In unilateral disease the cure rate was significantly higher (62%) than in systemic FMH (28%; p less than 0.03). Patients with strict bilateral disease were cured in 50%. We conclude: (a) PTA seems to be the treatment of choice in renovascular FMH because of a high cure and a low complication rate and (b) the outcome of curative interventions seems markedly influenced by the extension of FMH in these patients.