Bikiwhan is one of the oriental medicines that have been used for the treatment of tumors since ancient times. However, the mechanism of the drug action is not closely surved. This study was made to investigate the effects of Bikiwhan on the innate immunity were analysed by measuring the functions of phagocytes, and those of specific immunity were analysed by measuring T and B cells activities. The followings are the results obtained from this study : 1. Bikiwhan has direct cytotoxic effects against human lymphoma cell lines (K562) in a dose dependent manner. 2. An administration of Bikiwhan increased allogenic immune response in the mouse. 3. An administration of Bikiwhan increased the antibodies formation against SRBC. 4. An administration of Bikiwhan enhanced the apperance of rosette forming cells in the spleen. 5. An administration of Bikiwhan decreased the delayed-type hypersensitivity against dinitrofluorobenzene. 6. An administration of Bikiwhan has no effect on natural killer cells. 7. Bikiwhan increased the phagocyte activity of peritoneal macrophages in vitro and in in vivo as well. 8. Bikiwhan depressed the formation of reactive oxygen intermediated in vitro and in vivo as well. 9. Bikiwhan has the capacity to make peritoneal macrophages secrete nitric oxide. The above results demonstrate that Bikiwhan has enhancing effects of immune responses against tumors by decreasing tissue demages caused by immune responses.