Severe bronchial hemorrhage in 13 patients with cystic fibrosis was treated by catheter embolization of bronchial arteries. Indications were either excessive bleeding persisting for several days, or bleeding serious enough to interfere with pulmonary drainage and recurring over weeks or months. In follow-up ranging from one to 30 months, cessation of major bleeding was achieved in 12 of 13 patients (93%), although 5 of 13 patients (40%) did have recurrence of minor hemoptysis. No neurologic or other major complications were encountered. However, there are potential risks and this approach at present should be limited to patients with life-threatening bleeding and carried out only by experienced angiographers.