Abstract: The effects of isoprinosine on the immunofunctions of the mice were investigated.The results showed that isoprinosine could enhance the proliferation of theconcanavalin A-induced lymphocyte both in vivo and in vitro of the mice. Butthere was no effect on lymphcyte by single drug treatment. Compared with thecontrol groups. isoprinosine also could enhance the furction of macrophages andaugment serum lysozyme concentration significantly, it could enhance the immu-noresponse to the SRBC too. These suggest that isoprinosine is a promising immu-noregulator which can enhance the immune functions of the mice, but the effecton immune functions for human being should be further studied.