In 1984 a 42-year-old female complaining of general malaise and loss of strength in the proximal muscles of the limbs came to the 2nd Department of Internal Medicine for an examination. From her high CPK value, electromyogram, muscle biopsy, etc., she was diagnosed as having polymyositis. Initially she responded well to steroids, but a year later the condition recurred. Treatment with various methods such as the immunosuppressants methotrexate and azathioprine, steroid pulse therapy and plasma replacement were tried without success. In September 1991, the patient's CPK value remained abnormal at about 800mU/ml. According to the Oriental Medical viewpoint, the condition was diagnosed as Kidney yin Deficiency. Rokumi-gan was therefore administered daily (7.5g/day) for a period of 80 days. The CPK value was brought down to the vicinity of 200mU/ml, and the feeling of general malaise and lack of strength in the proximal muscles of the limbs was improved. However, due to the persistence of edema in the lower limbs, the Kampo formula was changed from Rokumigan to Chorei-to, also administered at a dosage of 7.5g/day. This reduced the edema and normalized the CPK value to the 100mU/ml range. During this period, steroid administration was maintained with prednisolone (30mg/day). At present, with the improvement in the CPK value, steroid administration is gradually being reduced.