IL-2 is a biotherapeutic drug and a biological response modifier. This drug has not been approved by the Food and Drug Administration for general use but continues to undergo clinical trials. Candidates for this therapy are patients with advanced carcinoma that has not responded to standard modalities of treatment. Administration of IL-2 can lead to systemic toxicity, which usually appears to be dose-related. As a result, high-dose therapy requires intensive care. The critical care nurse assesses and documents side effects that occur as a result of IL-2 therapy and must be aware of both the physical and psychological needs of the patient. Through successful assessment and intervention, the nurse can gain the knowledge required to manage, both physically and psychologically, patients who are undergoing this therapy.