We describe a 56-year-old woman with Stewart-Treves syndrome who had severe dyspnea from a pleural effusion caused by metastatic angiosarcoma in the right lung. Tumor-infiltrating lymphocytes (TIL) in the pleural effusion were cultured and expanded in vitro in the continuous presence of recombinant interleukin 2 with periodic stimulation by CD3 antibody. The expanded TIL were administered intrapleurally seven times at 1- to 4-week intervals in combination with intravenous infusion of recombinant interleukin 2. A panel of T-cell clones was also obtained from TIL. Immunotherapy dramatically improved the patient's dyspnea and pleural effusion. A CD4+ T-cell clone and a CD8+ T-cell clone established from TIL had specific cytotoxicity to the tumor cells.