Pulmonary arteriovenous malformations (PAVM) are high-flow, low-pressure shunts, consisting of a single feeding artery connecting via an aneurysmal sac to a draining vein. The aneurysmal connection is referred to as an aneurysmal sac. The "filter capacity" of the pulmonary capillaries is lost and results in predisposition to brain abscess, stroke, and transient ischemic attack and, when multiple, dyspnea, because of right-to-left shunting and hypoxemia. PAVM are markers of hereditary hemorrhagic telangiectasia (HHT). Up to 30% of patients with HHT have PAVM complicating their disorder. Left untreated, 50% of patients with PAVM will develop disabling or fatal complications. In addition to stroke and transient ischemic attack syndromes due to passage of paradoxical emboli through the PAVM, rupture of the aneurysmal sac, particularly in the third trimester of pregnancy, can lead to fatal hemoptysis or hemothorax. Finally, brain abscess or more obscure musculoskeletal or spinal infections may be secondary to PAVM. Since detachable silicone balloons are no longer available, we have developed precise techniques for closing pulmonary malformations using pushable fibered coils. It is not the coil that is so important, but it is the use of coaxial or triaxial catheters that allow for precise placement of the coil. Cross-sectional occlusion is essential for embolization of PAVM and this is achieved using the "anchor" or "scaffold" technique. Our recent results indicate permanent involution of treated malformations with a 3% recurrence rate. All patients should be assessed for other manifestations of HHT before treatment and they are best followed in one of the 20 HHT Centers worldwide (www.hht.org).