A 37-year-old man was sent to our department from the Radiology Department on July 19, 1984 with the diagnosis of right renal cell carcinoma with metastases to the right humerus and bilateral lungs. He was nephrectomized immediately and administered 10 X 10(6) units of alpha-interferon i. m. every other day for 3 months during the admission and 30 X 10(6) units once a week for more than 3 months after discharge. Although in addition to humeral and lung metastases, brain metastasis was found a week after the operation, interferon showed a remarkable effect and produced get a complete response in the humeral and brain metastases, and partial response in the lung metastasis. We think this is, perhaps, the first case of CR in brain metastasis so far. We conclude that interferon can be the first choice drug as an adjuvant chemotherapy against renal cell carcinoma.