We report a patient with a severe inclusion body myositis (IBM). His illnes
s was unusual in terms of a rapid progression, high creatine kinase levels,
and complication with interstitial pneumonia. He responded well to immunos
uppressive agents such as corticosteroids, cyclosporin A, cyclophosphamide,
and immunoglobulin. The present patient indicates the wide range of the di
sease, and that immunosuppressive agents may be useful for treatment of IBM
.