Metastatic renal cell carcinoma has a poor prognosis. The value of immunotherapy with IFN-alpha and IL-2 both as single agent or as the combination is extensively investigated. The optimal dose and schedule is not known. In various studies response rates vary between 10 and 40%. The duration of response is variable. For a partial response a median duration between 10 and 12 months is given. Complete responses are sometimes long-lasting (a couple of years). The toxicity is drug, dose and schedule dependent. On the basis of a number of prognostic factors, such as performance score, time between the initial diagnosis and the treatment of metastases and the number of metastatic sites, patients can be divided in different prognostic groups. Patients who are classified in the good or intermediate prognostic group may have an improvement of their survival after immunotherapy and therefore they are candidates for immunotherapy.