Importance; The use of endoscope for the ear has opened up new approaches to treat cholesteatoma surgically and reduce residuals. The endoscope can be used as an adjunct to the microscope or by itself. Aims and objectives:1. To evaluate the use of endoscopy in identifying the cholesteatoma remnant at the time of primary surgery with the operating microscope.2. To evaluate the effectiveness of endoscopy in assessing limited disease during cholesteatoma surgery.Design: A hospital-based, interventional, non-randomized, non-comparative and prospective study was done in 116 ears with acquired cholesteatoma. At the time of the surgery, the endoscope was used to study and identify the extent of the disease. After completion of the surgery by the standard inside-out technique using microscope and drill, the endoscope was used to identify the cholesteatoma remnants if any.Setting: This study was done in a tertiary care hospital.Participants: 116 patients with acquired cholesteatoma that were operated on. Main outcome measure:The proportion of residual disease identified with the help of endoscope at the end of standard surgery using microscope and drill. Secondary outcome measure was the proportion of cases in which endoscope was useful in decision making intra-operatively. Results:Out of 116 patients operated with the microscope, 13 had a cholesteatoma remnant at the end of surgery which was missed by the microscope but identified with the oto-endoscope. The sinus tympani was the commonest site of cholesteatoma remnant. Also in 7 cases, the endoscope helped in limiting the dissection by better identification of the extent of disease as compared to microscope during surgery. Conclusion and relevance:Endoscope is a useful adjunct to the operating microscope in cholesteatoma surgeries. It is useful in not only identifying residual disease but also in decision making by identifying the extent of the disease intra-operatively.