·AIM:To discuss the clinical effect of mitomycin C in nasal endoscopic dacryocystorhinostomy for curing chronic dacryocystitis.·METHODS:Totally 65 patients with chronic dacryocystitis were divided into treatment group and control group;the patients in treatment group received 0.4mg/mL of mitomycin C when undergoing nasal endoscopic dacryocystorhinostomy,while the patients in control group received no medicine when undergoing traditional dacryocystorhinostomy.After 12 months follow-up the patency of lacrimal passage was observed,and the area of ostomy with nasal endoscope and mycteric recovery was examined.·RESULTS:Of all 39 eyes 35 patients in treatment group,38 eyes were cured,the cure rate was 97%;of all 34 eyes 30 patients in control group,26 eyes were cured,the cure rate was 76%;a significant difference was found in cure rate between two groups(P<0.05).·CONCLUSION:The application of mitomycin C in nasal endoscopic dacryocystorhinostomy is a simple,safe and effective way to treat the chronic dacryocystitis,because it possesses the advantages of small injuries of tissue,few scar of face,small atresia of ostomy and high successful rate.·