Abstract: The aim was to explore the antitumor effect of mistletoee extract （ME） on resisting tumor in mice with sarcoma S 180 in the study.Sarcoma180 mice bearing in solid form and ascites form respectively was injected into sarcoma with the dosage of 1.65 mg/（kg·d） to 15 mg/（kg·d） of ME for 9 days continuously, then these indexes respectively was examined including tumor weight, inhibitory ratio of tumor growth, number of spleen nucleated cells, spleen index （SI）, survival time and histopathology of tumor tissues and several viscera. Inhibitory ratio of tumor growth reached 14.7 % to 28.3 % after injected, and the treated in survival time and SI both were higher than that of the control （P〈0.01）, in histology, the treated tumors was encapsulated in firm connective tissue, while the control was loosely structured connective tissue.Seen from the result, there is an anti-tumor effect of the mistletoe in vivo, and it may be associated with the increase in protecting spleen function.