BACKGROUND Thromboembolic episode, especially cerebral vein thrombosis, is a rare extraintestinal complication of ulcerative colitis. In world literature less than 100 cases are reported. Although the existence of coagulation alterations and fibrinolysis have been suggested, the exact mechanism of hypercoagulability in patients with ulcerative colitis is still unknown. METHODS The authors report of a 35-year-old female patient with ulcerative colitis, that has existed for several years. She developed strong cephalgias without further neurologic symptoms in an acute attack of her disease. Magnetic resonance imaging led to the diagnosis of an extensive acute cerebral vein thrombosis. Other possible reasons for a coagulopathy were excluded. CONCLUSIONS Cerebral vein thrombosis is a rare, but severe complication of ulcerative colitis. Thus, the presence of neurologic symptoms in a patient with known ulcerative colitis should lead to immediate diagnosis and treatment.