Objective To evaluate the effects of low-dose 125I seeds to the esophagus fibroblast cell proliferation in vitro.Methods The titanium wire was implanted in the beagle dog's esophagus to induce fibroblast proliferation,and the esophageal tissue was removed after two weeks and cultured in vitro.The 125I seeds with different dose commonly used were chosen to irradiation fibroblast in group B (11.1 MBq × 9)、C (22.2 Mbq ×9) 、D (33.3 MBq ×9) for 72 hours,while in control group no 125I seeds were used.After irradiation,cells were collected.MTT and AnnexinV/PI double staining were performed respectively to evaluate the effects of 125I seeds in cell proliferation and apoptosis.Results The inhibition rate respectively:(26.81 ± 1.96) ％、(34.52 ± 3.21) ％ and (45.33 ± 2.59) ％ ; the apoptosis rate respectively:(6.73 ±0.57)％ 、(13.11 ± 1.39)％ and (15.23 ± 0.90)％.There were significant differences among the experimental groups and between every experimental group and the control group.Conclusion The three doses of 125I seeds could significantly inhibit the fibroblast proliferation and promote cells apoptosis,of which 33.3 MBq 12sI seed was the most significant.