This study tested the effect of intratumoral injection with activated tumor-infiltrating lymphocytes (TIL), and simultaneous administration of recombinant interleukin-2 (rIL-2) and interferon α (IFN-α) (LII protocol), on mouse liver tumor. Group I ( n = 10) served as the controls. Group II ( n = 17) received rIL-2 + IFN-α schedule. Group III ( n = 20) received the LII protocol. A total of 5 × 10 6 of TIL were injected into 4 sites of a tumor in a single treatment. rIL-2 (1 × 10 6 IU) on the first day and IFN-α (1 × 10 5 IU) on the second day were alternately given with a total of 10 treatment doses that were completed in 20 days. Tumor remission or regression rates of 29% and 40% were obtained in groups II and III, respectively, but no remission was obtained in the controls. A large number of TIL were also observed in the tumors treated with the LII protocol. Making comparisons between the control group and IL-2 + IFN-α schedule, and the control group and LII protocol, the ratios of cytolytic activity of TIL in vitro were 0:32 and 0:57, respectively. We conclude that the LII protocol appears to be more effective in the treatment of mouse liver tumor than the IL-2 + IFN-α schedule, and that it may be a new promise for the treatment of patients with liver malignancies.