Aim: The aim of the present study is to evaluate post-operative factors involved in the causation of cavity problems. Materials and Methods: This prospective observational study was conducted in the Department of ENT, Patna Medical College and Hospital Patna, Bihar, India for 1 year. Total 135 patients who underwent canal wall down mastoidectomy were included in this study. Results: The incidence of postoperative cavity problems in our set up is 37.04 %. Maximum incidence of cavity problem was found between 30–40 years (88%) followed by 10-20 years (22%) and 40-50 years (24%). Of the 50 patients with cavity problems, 68% were of sclerotic mastoid and 8% were of cellular mastoid and 24% were of diploeic mastoid. 40 surgeries were done under general anaesthesia. Of the 50 problem cavities, 46 had prolonged discharge from mastoid cavity as the main problem (92%). Accumulation of wax in the cavity was present in 18 cases (36%). Vertigo persisting beyond the immediate postoperative period was present in 11 cases (22%). Perichondritis of pinna was found in 3 case (6%). Persistence or/development of facial palsy in post-operative period was found in 12 cases (24%) and recurrent cholesteatoma was seen in 8 cases (16%). 4 Cases had postoperative wound infection (8%). Out of 135 cases, 22 cases had a large post-operative cavity. Conclusion: The incidence of post mastoidectomy cavity problems in this study was found to be 37.04%. Increased incidence of cavity problems was found predominantly in 30-40 age groups.