Like interferon-alpha, interleukin 2 (IL2) is active on metastatic kidney cancers, which are regarded as chemoresistant tumors. Out of 20 to 30% objective responses, 5 to 10% complete remissions are reported with various IL2 delivery schedules. The considerable toxicity is well mastered at present, thus allowing treatment in non-intensive care departments, or even in an ambulatory mode for subcutaneous administration. Even though Interleukin 2 has been authorized for sale in France, optimal mode of administration, the role of the IL2-interferon-alpha combination or the predictive factors of response to treatment still raise many questions.