AIM:To discuss the clinical effect of mitomycin C in nasal endoscopic dacryocystorhinostomy for curing chronic dacryocystitis. METHODS:Totally 57 cases(63 eyes) with chronic dacryocystitis were performed the nasal endoscopic dacryocystorhinostomy combined with mitomycin C. The clinical effect was observed. RESULTS:All the patients were followed up for more than six months，54 cases (59 eyes, 95%) were cured，3 cases (4 eyes, 5%) were improved. Effectiveness was 100%. CONCLUSION:The application of mitomycin C in nasal endoscopic dacryocystorhinostomy is a safe and effective way to treat the chronic dacryocystitis.Because it possesses the advantages of higher cure rate，no scars of face and little hemorrhage and accurate location， at the same time, mitomycin C can prevent the growth of granulation tissue and the formation of fibrous scar，and reduce the atresia of ostomy，so it can increase the success rate of operation.