AIM:To study the effect of ring silicone tube implanta-tion combined with mitomycin C for the treatment of upper lacrimal duct obstruction.METHODS:Eighty-nine cases (116 eyes) with upper lacrimal duct obstruction underwent the procedure of intubation in outpatient clinic:tears points obstruction(14 eyes),lacrimal duct obstruction (38 eyes),tears explorer obstruction (64 eyes). The patients were randomly divided into 2 groups. Group A consisted of 44 cases(58 eyes):tears points obstruction(6 eyes),lacrimal duct obstruction(20 eyes),nasolacrimal duct obstruction(32 eyes). Group B consisted of 45 cases(58 eyes):tears points obstruction(8 eyes),lacrimal duct obstruction(18 eyes),nasolacrimal duct obstruction (32 eyes). The materials were silicone tube,duct expansion wire which was made by myself. Two-canalicular-nasolacri-mal duct were installed ring silicone tube. The time of extubation was after 3-6 months. If the patients were also with nasolacrimal duct obstruction,inverse ball silicone tube implantation in nasolacrimal canal should be performed immediately after the extubation of the ring silicone tube. What group B distinguished from group A was indwelling duct expansion wire which is immersed in 0.25mg/mL mitomycin C for 3-5 minutes; lacrimal duct was washed regularly after extubation of ring silicone tube,and the patients were followed up for 2 years.RESULTS:The cure rate of group A was 72.4%,the cure rate of group B was 93.1%. There were significant differences in recovery rate between the two groups(P<0.01).CONCLUSION:The method of installing ring silicone tube under mitomycin C can improve the success rate of surgery and can be a better way to cure upper lacrimal duct obstruction.