We review the current literature on systemic therapy for patients with metastatic renal cell carcinoma. Metastatic renal cell carcinoma remains highly resistant to chemotherapy and hormonal agents not justifying its use as a single agent. Interleukin-2 immunotherapy is the most effective treatment for metastatic renal cell carcinoma available today. There is evidence that interleukin-2 improves survival and yields long-lasting remissions in selected patients; the optimal dose and schedule still need to be defined. Response rates in patients treated with subcutaneous interleukin-2 are similar to those achieved with high-dose bolus intravenous applications. Questions remain concerning quality of life and benefit-to-risk ratio with respect to immunotherapy in individual patients. Different routes of administration of interleukin-2 such as local application, promise to improve quality of life and survival times.