Adoptive transfer of autologous lymphokine-activated killer cells (LAK) in conjunction with recombinant interleukin-2 (rIL-2) has been reported to produce significant regression in metastatic disease in patients with advanced cancer. In an effort to confirm the results reported by the Surgery Branch of the National Cancer Institute, the same IL-2/LAK regimen was used in cancer patients at six extramural cancer centers. In this report we will review our experience with mononuclear cell removal from the blood of cancer patients using apheresis technology and extracorporeal handling of these cells to generate a selective, highly cytotoxic cell population.