Object: To determine outcomes of endoscopic assessment of the Aditus Patency in Mucosal COM with Sclerosed Mastoid during tympanoplasty. Methods: 50 patients presenting with inactive tubo-tympanic CSOM with sclerosed mastoid. Antrotomy with tympanoplasty were done for all patients. The intraoperative patency of the aditus was assessed by microscope and 30º otoendoscope. Results: 20 (80%) patients of endoscopic group compared to 10 (40%) patients in microscopic group showed graft take with statistically significant difference (p = 0.025). Conclusion: Otoendoscopyis a minimally invasive surgery and could be utilized efficiently to improve the visibility of aditus and then dealing with any pathology in mucosal COM with sclerosed mastoid during tympanoplasty. Summary at glance: 50 patients presenting with inactive tubo-tympanic CSOM with sclerosed mastoid. The intraoperative patency of the aditus was assessed by microscope and 30º otoendoscope during tympanoplasty.