Beh?et's disease is an unusual medical condition in central Europe and North America, however more common in Turkey and Japan. It was originally described in Turkey, characterized by recurrent oral ulcers, genital ulcers and also uveitis. A variety of vascular lesions such as venous occlusions, arterial aneurysms and varices account for the high rate of morbidity and mortality with this disease. Arterial aneurysms most commonly occur in the abdominal aorta, femoral arteries and in the pulmonary arteries. To our knowledge there have been seventeen documented reports of patient's with Beh?et's disease combined with aneurysms of cerebral arteries. We describe a patient with Beh?et's disease and subarachnoid haemorrhage due to a ruptured cerebral aneurysm. © Springer-Verlag 2005.