Objective:To explore the antitumor effects of ethanol extract from Ventilago leiocarpa Benth(EEVLB) on sarcoma 180 (S180) tumor-bearing mice and the potential mechanism.Methods:Sixty mice were randomly assigned to 6 groups according to a random number table:normal group,model group,5-fluorouracil(5-FU) group (0.02 g·kg-1),and high-,medium-,low-dose EEVLB groups (100,84,and 56 g of raw material·kg-1 body weight,respectively),with 10 mice each group.All treatments were given once daily for 10 consecutive days.Effects of EEVLB on inhibiting tumor growth and immune function in mice were evaluated among all groups after the treatments by detecting tumor inhibition rate,organ index,serum levels of interleukin (IL)-2,-6,-10,CD3+CD4+ T lymphocytes,CD4+/CD8+ ratio,caspase-3 and Bcl-2.Results:EEVLB with different concentrations achieved inhibition of tumor growth in vivo,wherein the high-dose group showed the most significant reduction in tumor weight and increased apoptosis of tumor cells (P＜0.05).In addition,both net weight gain and spleen index of mice showed uptrend in EEVLB treatment groups (P＜0.05).Besides,serum levels of IL-2 and IL-6,percentages of CD3+CD4+ T lymphocytes and ratio of CD4+/CD8+ in peripheral blood were elevated in high-and medium-dose EEVLB groups compared with the model group (P＜0.05).Also,upregulation of caspase-3 and downregulation of Bcl-2 were observed at protein levels in the high-dose EEVLB group (P＜0.01).Conclusions:EEVLB exhibits promising antitumor activity in vivo.This effect might be due to activation of apoptotic signaling pathway,increase of cytokine levels and enhancement of immune function in tumor-bearing mice.