Cholesteatoma is the most severe middle ear disease. In most cases cholesteatoma results from under-aeration of the middle ear cleft. It is characterized by otorrhea and hearing loss, and may lead to severe complications, intra- and extra-cranial. There is no non-surgical treatment for cholesteatoma. Surgical treatment is the only option. Cholesteatoma is diagnosed by micro-otoscopy. When cholesteatoma is suspected and otoscopy is inconclusive, imaging is mandatory. The goal of treatment in cholesteatoma is to achieve a stable and safe ear. In most cases, upon diagnosis, cholesteatoma is quite extensive and mastoidectomy is needed. Choice of surgery [Canal wall up mastoidectomy with tympanoplasty (the more conservative alternative), Canal wall down (radical) mastoidectomy with meatoplasty or Canal wall down (radical) mastoidectomy with reconstruction of external ear canal, tympanoplasty and mastoid obliteration], depends on the extent of the disease, the anatomic relationship between the sensitive structures that protrude into the walls of middle ear and mastoid cavities and the bony destruction that had already been caused by the disease. Hearing rehabilitation should lead to a stable, predictable, symmetric and as close as possible to normal hearing threshold. In many cases the solution is external or implantable hearing devices. Cholesteatoma has a high recidivism rate that leads to repeated surgery. In order to diagnose and treat cholesteatoma recidivism, a structured follow-up is needed after cholesteatoma surgery, with periodical otoscopy (every 6-12 months) and MRI (every 1-2 years). When cholesteatoma recidivism is diagnosed, surgery is indicated before the disease grows and becomes infected.