To assess inhibition mechanisms of a Phellinus igniarius (PI) extract on cancer, C57BL/6 mice were orallytreated with PI extractive after or before implanting H22 (hepatocellular carcinoma ) or B16 (melanoma) cells.Mice were orally gavaged with different doses of PI for 36 days 24h after introduction of H22 or B16 cells. Micein another group were orally treated as above daily for 42 days and implanted with H22 cells on day 7. Thenthe T lymphocyte, antibody, cytokine, LAK, NK cell activity in spleen, tumor cell apoptosis status and tumorinhibition in related organs, as well as the expression of iNOS and PCNA in tumor tissue were examined. The PIextract could improve animal immunity as well as inhibit cancer cell growth and metastasis with a dose-responserelationship. Notably, PI’s regulation with the two kinds of tumor appeared to occur in different ways, since theantibody profile and tumor metastasis demonstrated variation between animals implanted with hepatocellularcarcinoma and melanoma cells.