Middle ear cholesteatoma is defined as a cystic lesion lined by a keratinizing squamous epithelium which have a tendency to destroy the surrounding bony structures. There are many theories to explain the pathogenesis of the cholesteatoma but up to date only two of them are widely accepted by many authors, the invagination and invasion theory. Cholesteatoma may arise at any site of the tympanic membrane but may behave very differently according to their site of origin. In this study we made a subdivision of the cholesteatoma types into attic, sinus and tensa cholesteatoma according to the Tos’s classification to evaluate the clinical difference between the cholesteatomas of different site of origin.