Abstract: Life-prolonging effects of β-Carotene (β-C ) on ehrlich ascites carcinoma (EAC)-bearlng mice were determined in the study. The results showed the mice life was prolonged, thymus index and spleen index were increased with the administration of β-C 5mg and 7.5mg. kg^-1) (P＜0.05 for both dose groups), PHA-induced lymphocytes proliferation was enhanced by all dose groups (β-C 2. 3mg, 5mg, 7. 5mg·kg^-1) (P＜0.05 for low dose group and P＜ 0.01 for both of medium dose group and high dose group). It is suggested that β-C can inhibit EAC, and it may be associated with enhancement of β-C on tumor immunity.