The purpose of this research was to investigate the immuno-modulatory effect and anti-carcinogenic property of Cordyceps militaris(CM) and/or Paecilomyces japonicus (PJ). The proliferation of cultured splenocytes and thymocytes were enhanced by the addition of 10 ㎍/ml of CM and/or PJ. B lymphocytes subpopulation in splenocytes were increased both CM and/or PJ administered(p.o. for 7 days)-mice. Thymic T lymphocytes, especially TH cells were significantly increased in CM-administered mice. CM and/or PJ treatment inhibited the cell viability of L 1210 mouse leukemia and HL60 human leukemia cells and induced the apoptosis of L1210 and HL60 cells. In addition, CM and/or PJ increased the hemaggutination(HA) titer against SRBC. These results suggest that CM and/or PJ have an immuno-modulatory action and anti-carcinogenic property.