Twenty-three patients with advanced renal cell carcinoma were treated with subcutaneous injections of interleukin-2 (IL-2) and interferon-alpha (IFN-alpha). IFN-alpha (5-10(6) U/m2) was injected on day 1 of the 1st week of a treatment cycle of 6 weeks and high doses of IL-2 (20.10(6) IU/m2) on days 3, 4 and 5. In the 2nd and 3rd week IFN-alpha (dose as above) and low doses of IL-2 (5.10(6) IU/m2) were injected on days 1, 3 and 5. The treatment from the 4th to the 6th week corresponded to that of the 1st to 3rd week. In cases of remission or stable disease the treatment schedule was repeated as a rule once or twice. In 12 of the 23 cases nephrectomy had been carried out previously. Complete remission lasting 4 + months and partial remission lasting 2 months were achieved in two patients with lung and skeletal metastases. A stable state of the disease lasting 1-7 + months was observed in 11 cases. Ten patients showed progression of the disease after the first treatment cycle. Thus, the overall objective response rate was 9%. The side effects were only slight and corresponded to WHO toxicity grade I (n = 8) and grade II (n = 15). In two cases the first treatment cycle could not be finished.