Thromboembolic disease is a well-recognized but very uncommon complication of inflammatory bowel disease. The mechanisms of the increased risk of thrombosis are not well understood: although several coagulation abnormalities have been described in inflammatory bowel disease patients, it is not clear whether they actually contribute to hypercoagulation or whether they are nonspecific markers of inflammation. Antiphospholipid antibodies (anticardiolipin antibodies and/or lupus anticoagulant) have recently been associated with an increased risk of thrombosis, particularly cerebrovascular disease in young patients. We report the case of a 33-yr-old female with severe ulcerative colitis at first attack who developed thrombosis of the superior and inferior longitudinal dural sinuses. No risk factors for thrombosis or coagulation abnormalities were observed; however, lupus anticoagulant was detected in the serum. The patient was successfully treated with osmotic agents, prophylactic anticonvulsant, and antiplatelet therapy, combined with i.v. steroids. After 6 months, the colitis is in remission, and the neurological recovery is good even if not yet complete.