Thirty-six patients with metastatic melanoma were entered into a study of the therapeutic efficacy of adoptive immunotherapy with high-dose interleukin-2 (IL-2) and lymphokine-activated killer (LAK) cells. Thirty-two patients who received all components of the therapy are evaluable for response, and all patients are evaluable for toxicity. Sites of disease included lung, liver, subcutaneous nodules, and intra-abdominal metastases. One complete response (CR) and five partial responses (PRs) resulted from treatment (19% response rate). The median response duration was 5 months, with the durable CR continuing at 31+ months and one durable PR continuing for 13 months. Sites of response included lung, liver, subcutaneous nodules, and lymph nodes. Response, response duration, or site of response did not correlate with the total dose of IL-2 administered, rebound lymphocytosis, or the number of LAK cells infused. Toxicity included hypotension, fluid retention with a "capillary leak syndrome" in most patients, and transient multiorgan dysfunction that resolved promptly after the completion of therapy. Adverse cardiac events occurred in 16% of patients, with one myocardial infarction leading to a death. This study confirms the activity of the initial IL-2/LAK cell regimen in metastatic melanoma reported by Rosenberg et al, supporting the concept of adoptive immunotherapy as an important new treatment approach for this disease.