ObjectiveTo investigate the effect of interstitial brachytherapy with 125Ⅰon human esophageal carcinoma implanted in nude mice. MethodsAnimal model simulating human esophageal carcinoma was established by subcutaneous implantation of cultured Eca-109 cell lines into nude mice.The mice were randomly divided into 3 groups,namely control group (saline plus empty seed),125Ⅰ seed group (22.2 MBq×1 seed),and DDP group (cisplatin at the dose of 1 mg/kg),to receive corresponding treatment.The growth rate and the pathological changes of esophageal carcinoma were observed.ResultsThe animals were sacrificed 16 days after irradiation.The average tumor weight in control group,125Ⅰ seed group,and DDP group were (0.20±0.06) g, (0.12±0.03) g and (0.12±0.05 ) g,respectively (P<0.05).Pathological findings included degeneration and necrosis of the tumor cells.Compared to the control group,the necrosis areas in 125Ⅰ seed group and DDP group were significantly larger than those in control (P<0.05).Conclusion125Ⅰ seed brachytherapy in esophageal carcinoma could cause degeneration and necrosis of the tumor cells and had inhibitory effect on tumor growth.