We have treated 21 patients (13 female, 8 male) with pulmonary arteriovenous malformations (PAVMs). Mean age at diagnosis was 37.5 years (range, 15 to 72 years). Presenting symptoms included dyspnea on exertion (67%), hereditary hemorrhagic telangiectasia (57%), and major neurologic events (33%). In our early experience, 8 patients had no specific treatment; their case histories illustrate the major neurologic complications of untreated PAVMs. Nine patients (8 primarily, 1 after recurrence) underwent conservative surgical excision; 4 had lobectomy, and 5 had segmentectomy or subsegmental excision. One patient underwent staged bilateral thoracotomies for multiple bilateral lesions. The arterial oxygen tension was found to increase after excision of large or solitary PAVMs. All surgically treated patients were relieved of dyspnea, and none had postoperative recurrence of PAVMs or neurologic complications related to PAVMs. Five patients underwent balloon occlusion of PAVMs. Two patients chose to have solitary PAVMs occluded rather than undergo thoracotomy. One underwent surgical excision 5 years later, and the other required repeat balloon embolization 4 years later when recanalization of the PAVMs was documented. Three patients with numerous PAVMs received palliation with multiple balloon embolizations. The high incidence of associated major neurologic complications mandates aggressive treatment of PAVMs whenever feasible. Conservative surgical resection remains the treatment of choice. Balloon embolization offers an alternative therapy for patients who are poor surgical risks or those whose lesions are too numerous to resect.