The purpose of this research was to investigate the immunoregulatory effect and the leukemia cell apoptosis of EtOH extract of OGAPI(OGP). The proliferation of cultured splenocytes, thymocytes and mesenteric lymph node cells were enhanced by the addition of OGP. Splenic and thymic T lymphocytes, especially TH and Tc cells were significantly increased in OGP-administered mice. OGP markedly increased the production of γ-interferon in mice serum and accelerated the phagocytic activity in peritoneal macrophages. OGP treatment enhanced the apoptosis of L1210 mouse leukemia and Jurkat, Molt4 human leukemia cells, and increased the expression of apoptosis-related ICE, c-myc, p53 gene in Jurkat cell. These results suggest that OGP have an immunoregulatory action and anti-cancer activity.