A 46-year old woman experienced an episode of arterial desaturation despite administration of 100% oxygen during anesthetization for an elective laparoscopy. Further evaluation revealed a giant pulmonary arteriovenous malformation (PAVM) with right-left shunt associated with previously undiagnosed hereditary hemorrhagic telangiectasia (HHT, Morbus Osler- Weber-Rendu). The PAVM was treated interventionally with an Amplatzer duct occluder. Transcatheter embolization of the PAVM was well tolerated with symptomatic and hemodynamic improvement. CT scan after six months demonstrated correct position of the duct occluder in the left pulmonary artery with nearly complete occlusion of the feeding vessel.PAVMs are rare direct communications between pulmonary arteries and veins, associated with HHT in the majority of cases and often presenting with dyspnea or major neurological complications due to paradoxic embolism. In this case report, we present a rational and stepwise diagnostic workup for this rare medical condition and show that transcatheter embolization is an appropriate treatment for larger malformations.