Multiple pulmonary arteriovenous malformations (PAVM) present a difficult management problem, since surgical resection is not feasible in most instances. Embolotherapy offers a viable alternative. Over a 2-year period, the authors used detachable balloons to treat 16 PAVMs in 5 patients, of whom 4 had severe hypoxemia and 1 had hemoptysis. Symptomatic improvement was achieved in all but 1 patient, in whom the largest PAVM could not be occluded because the balloon was too small. Two patients exhibited segmental pulmonary infarctions. Follow-up angiograms 4 months and 2 years after occlusion demonstrated persistent obliteration of 14 PAVMs without development of collateral supply; 2 required re-embolization due to enlargement of existing nonoccluded feeders. The authors feel that balloon embolization is a safe and effective treatment of PAVMs.