Abstract: Objective To investigate the effect of IL-18 on growth and apoptosis of Lewis lung cancer xenograft growth in C57BL/6 mice. Methods C57BL/6 mice implanted with Lewis lung cancer cells were randomly divided into two groups: IL-18 treatment group and bearing tumor model group. Seven days after tumor implantation, IL-18 and saline were given by intraperitoneal injection daily for 7 days. All the animals health status were monitored, the volume and weight of subcutaneous tumors were measured, the xenografts TUNEL was used to assess apoptotic index of tumor cells in the xenografts. Results IL-18 effectively inhibits the growth of xenografts by 75% and induces apoptosis of tumor cells in the xenografts while no significant effect on the health situation of animals was observed. Conclusion IL-18 maybe inhibits the growth of Lewis lung cancer by inducing apoptosis of tumor cells and it may be a potential novel therapy for Lewis lung cancer.