A 22-year-old Italian woman developed fungal aortitis after cardiac surgery for aortic insufficiency. She experienced two episodes of septic embolization and subsequently underwent replacement of the aortic root and initial ascending aorta by a homograft. The lumina of the ascending aorta, aortic arch and the origin of the innominate artery were completely filled with vegetation. From the involved tissue the phaeoid thermophilic hyphomycete Myceliophthora thermophila (Apinis) van Oorschot was isolated in pure culture. This is the second report of isolation of this fungus from humans and the first isolation of a human pathogenic strain of M. thermophila causing fatal vasculitis in a patient affected by cystic medial necrosis. A detailed morphological description of the isolate is also provided.