Interleukin 2 (IL2), like Interferon alpha (IFN), is active in metastatic renal cancer, considered to be a chemoresistant cancer. 20 to 30% of objective responses, including 5 to 10% of complete remissions are reported with various protocols of IL2 administration. The considerable toxicity is now well controlled, allowing treatments to be administered in standard wards or even on an outpatient basis by subcutaneous injection. IFN, generally given as long-term treatment, achieved average response rates of between 15 and 20%. Although IL2 and IFN have been granted Product Marketing Authorization in France, the modalities of optimal administration, the place of the combination of IL2-Interferon alpha and the factors predictive of response to treatment still remain unclear.