Abstract: Objective To investigate the time-effect and dose-effect of r-H2AX in different esophageal carcinoma lines after irradiation. Methods The dose-response(1，2，4，8Gy) and time-effect of r-H2AX in different esophageal carcinoma lines after irradiation were studied and compared by Western blot.Two cell lines of esophageal carcinoma (ECA109 and TE13) were radiated by 6MV-X ray of (1, 2, 4 and 8Gy) The cells and extracted proteins at 0.5, 1, 2, 4, 8, 12 and 24 h were collected and to study the dose-response and time-effect relationship of r-H2AX. Results (1) The first peak of r-H2AX expression gradually appeared in advance with the increasing radiation dose of ECA109 cells and TE13 cells. (2) r-H2AX within 24 hours recovered to the level before radiotherapy after low-dose irradiation in ECA109, The level recovered faster if the dose of radiation is lower; r-H2AX can not be recovered to the level before radiotherapy after irradiation of 1，2，4 and 8Gy within 24 h in TE13. (3) At 0.5, 1 and 2 h,the expression of r-H2AX in ECA109 and TE13 cells didn't increase with the increase in radiation dose. Conclusion The level of r-H2AX is more difficult to return to normal levels in TE13 cell line than in ECA109 cell line after irradiation which shows that TE13 is more sensitive to irradiation.