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Background Epigallocatechin-3-gallate (EGCG) has been demonstrated to have anti-neoplastic activity, but the effective concentration of EGCG and its possible mechanisms are uncertain. The study on the killing effects of EGCG on different digestive tract cancer cell lines can find target sites of its anti-neoplastic effect and provide a theoretical basis for its clinical application in the treatment of cancers. Methods Methyl thiazolyl tetrazolium (MTT) analysis was made to detect the differential sensitivities of eight digestive tract cancer cell lines to EGCG. The effect of EGCG on cell cycle distribution of sensitive cancer cell line was measured by flow cytometry. By polymerase chain reaction (PCR)-enzyme linked immunosorbent assay (ELISA) protocol, the influence of EGCG on telomerase activity of sensitive cancer cell line was also investigated. RT-PCR method was employed to detect the influence of EGCG on the expressions of hTERT, c-myc, p53 and mad1 genes in sensitive cancer cell line. Results EGCG exhibited dose-dependent killing effects on all eight disgestive tract cancer cell lines. The 50% inhibitory concentration (IC50) of SW1116, MKN45, BGC823, SGC7901, AGS, MKN28, HGC27 and LoVo cells were 51.7 μmol/L, 55.9 μmol/L, 68.5 μmol/L, 79.1 μmol/L, 83.8 μmol/L, 119.8 μmol/L, 183.2 μmol/L and 194.6 μmol/L, respectively. There were no apparent changes in cell cycle distribution of sensitive cancer cell line MKN45 48 hours after incubating with three different concentrations of EGCG compared with the controls. It was found that EGCG could suppress the telomerase activity of MKN45 cells, and the effects were dose- and time-dependent. After EGCG administration, the expression of hTERT and c-myc genes in MKN45 cells was decreased, that of the mad1 gene increased, and that of the p53 gene unchanged. Conclusions EGCG has dose-dependent killing effects on different digestive tract cancer cell lines. Administration of EGCG has no obvious effect on cell cycle distribution of sensitive cancer cell line MKN45. The anti-neoplastic activity of EGCG might be due to the inhibition of telomerase activity by means of its influence on hTERT and the up-stream regulation genes.