We report a case in which a regimen of interleukin-2 (IL-2) and interferon alfa (IFN-alpha) was effective against renal cell carcinoma with lung metastases. A 69-year-old man diagnosed with right renal tumor had not received treatment for 28 months. He was admitted to our hospital for treatment. Computed tomographic (CT) findings showed a right renal tumor 11.5 cm in diameter and multiple lung metastases. Right nephrectomy was performed, and pathological examination was renal cell carcinoma (clear cell carcinoma, G2, pT3a). A regimen of IL-2 and IFN-alpha was selected as an adjuvant therapy. He received 70 x 10(4) JRU/day of IL-2 (div) 5 times a week, and 600 x 10(4) IU/day of IFN-alpha intramuscularly 3 times a week for 8 weeks. Thereafter, both treatments were continued 3 times a week. CT scan showed a complete response on lung metastases 12 months and no recurrence has been observed on CT scan for 16 months after operation.