Cytokine therapy for patients with metastatic renal cancer is based on observations suggesting this neoplasm may be responsive to immunotherapy. Two cytokines, interferon-alpha (IFN-alpha) and interleukin 2 (IL-2) produce tumor regressions in 10% to 15% of patients with metastatic disease. Randomized trials demonstrate a modest survival advantage for patients treated with IFN-alpha. Combinations of IL-2 and IFN-alpha appear to be associated with improved response rates, but no demonstrable effect on survival. Additions of other cytokines (eg, GM-CSF) or chemotherapy to this combination has been investigated, but results do not suggest they enhance the outcome. Patient selection remains an important issue in this patient population. Individuals who are asymptomatic and have limited pulmonary or soft-tissue disease are most likely to benefit. The roles of immune dysregulation and the addition of novel cytostatic agents to these regimens are under investigation.