A 67-year-old man with a severe bleeding due to a high level of factor V inhibitor (maximum level of 350 Bethesda units) is described. Coagulation abnormalities improved initially during treatment with prednisolone in combination with cyclophosphamide. Subsequent treatment with either cyclophosphamide or cyclosporin alone was ineffective. After more than 2 years the inhibitor became undetectable after a prolonged period of high dose steroid therapy, but the patient remained steroid dependent. Therapeutic strategies for patients having a factor V inhibitor are discussed.