Treatment of renal cell carcinoma (RCC) has historically involved surgical removal of the primary tumor when localized, but when presented with metastatic disease the options have been limited. Approximately 30% of patients present with metastatic disease implicating a generally poor prognosis. The most significant advances have occurred in the area of immunotherapy as treatment for metastatic disease. This is because RCC is generally resistant to chemotherapy and radiation. One of the major successes of immunotherapy has been with interleukin-2 (IL-2). Initial IL-2 therapy proved difficult due to the significant administrative and side effect problems that occurred. This led to numerous variations in dose scheduling and delivery to identify an optimal beneficial way of administering IL-2. In addition, investigation also led to other immunotherapy agents such as interferon and cellular therapy.