Abstract: In this paper, we observed the anti tumor effects of a new TNFα variative （rhTNF αD11a） on murine Lewis lung cancer. C57BL/6 mice were implanted with cancer cells and tumor developed at the 7 th day. Different doses of rhTNFα D11a or natural TNF α were injected intramuscularly for 4 days or intra-tumor for 3 days. Mice were slaughted 1 day later, and the effects were estimated by the tumor depression ratio. It showed that the tumor depression ratio of every rhTNF α D11a dose was significantly higher than that of natural rhTNF α. Furthermore, intra-tumor injection was superior to intramuscular way.