Abstract: Use LAK cells, either alone or in combination with other immunotherapeutic agents has added a new list of alternatives to conventional antineoplastic regimens. Yet little information is available about the pathological changes occurring in patients treated with LAK cells. In this study, we reviewed the necropsy materials from 7 patients with a variety of malignancies. Death occurred at intervals ranging from hours to 215 days following the last dose of therapy. Lymphocytic infiltration of hart, liver and pulmonary fibrosis were demonstrated. A toxicity of LAK cell therapy is suggested.