Purpose: To compare the results of intra operative Mitomycin C application in DCR surgery compared to external DCR without Mitomycin C. Design: Randomized control trial. Methods: Total 80 patients of primary acquired nasolacrimal duct obstruction were divided into 2 groups on the basis of simple random sampling. Group- 1 contained 40 patients who received 0.02% solution of MMC at the osteotomy site during surgery and consider as the study group and group-2 contained another 40 patients who did not get MMC during surgery and considered as the control group. Patients were followed on 1st post-operative day, 1st week, 1, 3, 6 & 12 months interval. Patency of lacrimal passage was assessed by lacrimal syringing & patient's symptoms were recorded on each follow up Results: Data shows that there was statistically significant difference in the study showed 39 (97.50%) patients with patent lacrimal passage, only 1 (2.50%) patient was found blocked in their lacrimal drainage system in 1, 3, 6 Months and finally 1 year follow up time. On the other hand in control 34 (85.00%) patients showed patency of the drainage system after 1 year and 6 (15.00%) patients showed blockage and this results was maintained up to 1 year follow up after treatment. During the follow up period, no complication such as abnormal nasal bleeding, mucosal necrosis or infection were noted in any patients. Conclusion: Distinctly higher success rates were achieved in patients undergoing DCR with intra operative MMC as compared to those undergoing external DCR.