Immunoregulative action of 70% ethyl alcohol fraction of Cervus nippon was investigated in vitro. The fraction enhanced the proliferation of thymocytes and the population of CD4^+CD8^- single-positive. cells in thymocytes. CN-E enhanced [Ca^2+]_i, the production of TNF-α and IL-1β, and phagocytosis in peritoneal macrophages. The fraction did not induce the proliferation of splenocytes and DNA fragmentation in thymocytes. These results indicate that 70% ethyl alcohol fraction of Cervus nippon regulates immunological action by stimulating murine thymocytes and macrophages.