Antitumor effect of Traditional Chinese Medicine 901(TCM901) was studied using colonyforming assay and trypan blue exclusion rate.The results showed that TCM901 had inhibitory rate of 83.8% on colonyforming of carcinoma cell line H-7402.The inhibitory rate of TCM901 in vitro against H-7402,BCG-823,SPS and P388 reached 100%,respectively.These results suggested that TCM901 had markedly inhibition on the cancer cells and it might be a new-antitumor agent.