Aim : This study aimed at elucidating the effects of Inonotus obliquus on anti-tumor effects in vivo and immune-based characterization of the mushroom as a potential candidate for cancer remedy. Methods : To investigate the immunomodulatory effects of Inonotus obliquus, we investigated macrophage functions and NK cell activities through the measurement of NO production of macrophage, NK cell cytotoxicity and expressions of cytokines and genes regulating immune responses, in addition to pulmonary metastasis model in vivo. Results : Inonotus obliquus showed general cytotoxicity at high concentrations over the 100 ${mu}g/m{ell}$ on the both of normal and cancer cell lines. Inonotus obliquus showed both inhibitory and promotive effects on pulmonary colonization of CT-26 cell depending on period or route of administration in vivo. Conclusion : From these results, it cannot be concluded that Inonotus obliquus has cancer-specific activity. Furthermore, Inonotus obliquus has the provability to show adverse effects differently according to the concentration and the method of administration.