OBJECTIVE: To determine the inhibitory effect of EGCG on the Lewis Lung Cancer Model, to compare and preliminary to discuss the mechanism of the inhibitory effect of EGCG on the proliferation of A549 cell line and Calu-3 cell line. METHODS: Observed the inhibitory effect of EGCG on Lewis Lung Cancer in vivo. Compared the inhibitory effect of different dosages of EGCG on Calu-3 and A549 cell lines with WST-8 assay. Observed the opoptosis promotional effect of EGCG on Calu-3 cells. Compared the inhibitory effect of different dosage of EGCG on Calu-3 and A549 cell lines in PI cell number counting assay. RESULTS: EGCG inhibited the proliferation of Lewis Lung Cancer in vivo. Results of WST-8 assay showed that EGCG inhibited the proliferation of Calu-3 cell line in dose-dependent manner. However, A549 cell line showed sign of drug-resistance to EGCG. The inhibitory effect of EGCG on the proliferation of Calu-3 cell line through increasing apoptosis was observed with TUNEL assay. Cell number of Calu-3 was obviously decreased by treating of EGCG, but was not changed in A549 cell line. CONCLUSION: EGCG inhibited proliferation of Lewis Lung Cacer in vivo, and inhibited proliferation of Calu-3 cell line but didn't play the inhibitory role on A549 cell line in vitro. Copyright 2012 by the Chinese Pharmaceutical Association.