As there are a number of possible causes of syncope, differentiation between cardiovascular disease, neurogenic disease and other disorders is mandatory. Cerebral arteriovenous malformations (AVMs) are tangled anastomoses of blood vessels of varying calibre in which arteriovenous shunting occurs in a central nidus, which is the area towards which multiple feeding arteries converge and from which enlarged veins drain. We describe a clinical case of syncope caused by a large AVM discovered in a 66-year-old woman. The symptoms were probably related to an epileptogenic mechanism since the syncope disappeared following the administration of antiepileptic therapy. The anatomical, pathological and clinical aspects of AVMs are discussed.