We report 3 cases of young patients, 2 women and 1 man, who presented a cerebral venous thrombosis following intravenous treatment with high doses of corticosteroids. All of them presented a probable multiple sclerosis according to clinical, biological (CSF) and MRI criteria and were treated for the first time by a bolus of 1,000 mg of methylprednisolone OD during 5 days. All the usual causes of cerebral venous thrombosis were systematically excluded in all of them. The role of corticosteroid treatment in cerebral thrombophlebitis is discussed. All of them underwent a lumbar puncture a few days before corticosteroid treatment and the relationship between lumbar puncture and cerebral thrombophlebitis is also discussed. Cerebral venous thrombosis associated with corticosteroid treatment has rarely been reported. The relationship between corticosteroids and venous thrombosis has already been suggested but has never been clearly understood.