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) induce tumor regression in 10% to 15% of patients with metastatic disease. Randomized trials demonstrate a modest survival advantage for patients treated with IFN-alpha, as compared with chemotherapy. The combination of IL-2 and IFN-alpha appears to be associated with improved response rates, but has no demonstrable effect on survival. The addition of other cytokines (e.g., GM-CSF) or chemotherapy to this combination has been investigated, but results do not suggest that 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 addition of novel cytostatic agents to these regimens is now under way.