Dramatic efficacy of cyclosporin was observed in a patient with inflammatory pseudotumour in the liver. The 30-year-old male patient had suffered several attacks of high fever, polyarthralgia and lymph node swelling since 1981. In February 1989, abdominal CT showed multiple space-occupying lesions in his liver, and histopathology of the biopsied liver showed infiltration of plasma cells and lymphocytes with proliferation of collagen fiber, which was comparable to an inflammatory pseudotumour. In May 1990, a treatment regimen of cyclosporin A along with prednisolone was begun because he had been diabetic since March 1990. Within a few days of treatment, the high fever and polyarthralgia subsided, and leucocytosis of 32,000/mm3 and the increased CRP of 17.7 mg/dl were normalised within one month. A reduction of the size of the space-occupying lesions in the liver was observed on abdominal CT taken one month after cyclosporin treatment.