Cerebral thrombotic disease is a rare and nearly always fatal complication of ulcerative colitis. It is associated with a necrotizing vasculitis. We report a fatal case with a confusing neurologic picture arising from this complication. Autopsy revealed necrosis and hemorrhages affecting both cortical grey and white matter. Microscopic examination showed thrombosis of small and medium size vessels associated with hemorrhages and a necrotizing angiitis. Ulcerations, hemorrhages, pseudopolyps, and cryptic abscesses were found in the rectosigmoid region of the colon compatible with active ulcerative colitis. A sudden neurologic deficit in a patient with ulcerative colitis should direct attention to the consideration of a cerebral thrombotic event and the possibility of an associated cerebral vasculitis. Diagnosis may be strongly suggested by MRI or arteriography, but it may require confirmation by biopsy of the brain parenchyma and leptomeninges. A hypercoagulable state has been associated with the thrombosis. Anticoagulation has yielded successful results in some patients with cerebral thrombosis but the risk of massive intracranial and gastrointestinal bleeding preclude to establish clear indications. Neurologic improvement has been obtained with the use of steroids and cyclophosphamide.