OBJECTIVE To study the effects of Hubei Dioscorea bulbifera L.(DB) on immune function in mice. METHODS　KM mice were divided randomly into high, medium and low-dose group and control group. The mice in three dose groups were orally administered for 15 d with totally 1 000, 490 and 240 g·kg-1 body weight of DB respectively, while the mice in control group were treated with same volume of normal saline. Lactate dehydrogenase (LDH) test and carbon particle clearance test were performed to determine the functions of nonspecific immunity. Quantitative hemolysis spectrophotometry (QHS) method was performed to detect the functions of humoral immunity. α-Naphthy l.1-acetate esterase (ANAE) staining and methyl thiazolyl tetrazolium (MTT) assays were performed to measure cell-mediated immune function. RESULTS After 15-day administration, compared with the control group, DB markedly reduced the ability of phagocytosis of mononuclear macrophage in the high dose group. DB significantly enhanced the activities of natural killer cells, the antibody quantity of B cells, the quantity and proliferation of spleen T lymphocytes at the medium doses．CONCLUSION Overall, the high dose of DB was able to suppress immune functions in mice, while the medium dose can improve immune function.