Nonspecific tumoricidal effectors, called lymphokine-activated killer (LAK) cells, can be induced from the tumor-bearer's spleen in vitro. The adoptive transfer of such LAK cells to a patient with unresectable hepatoma was performed in this study. About 2.4 X 10(9) LAK cells generated from the autologous spleen were adoptively transferred to the patient via hepatic arterial catheter. Signs of toxicity encountered with LAK cell infusions comprised chills and fever only. Chemical studies of hepatic, renal, and hematologic parameters were normal; pulmonary function studies revealed no changes after infusion. With the transfer of LAK cells, serum alpha-fetoprotein (AFP) levels were markedly decreased and ascitic fluid retention was transiently reduced. Though the therapeutic effect was transient, these trials offered hope for a new therapeutic approach to unresectable hepatoma. Further, the availability of large amounts of recombinant interleukin-2 (rIL-2) may now make widespread use of this approach possible.