A male patient with post lingual hearing loss was implanted at 16 years of age with a Nucleus cochlear implant (Cochlear) in his left ear. Twenty two years later, he developed a cholesteatoma in relation to the mastoid portion of the facial nerve and in contact with the electrodes array. The cholesteatoma was removed and the ear canal reconstructed. There was no post-operative facial palsy and the cochlear implant was preserved. Although cholesteatoma is a rare complication of the cochlear implant surgery, it still can occur and can be a source of potential damage to the implant. The origin of this late-presenting complication could be excessive bone drilling associated with the pressure caused by the loop of the electrodes array on the posterior canal wall. Implanted patients must have a close and particular long-term follow-up, especially when a surgical breach of the canal wall or a tear of the tympanic membrane have occurred during surgery, as well as in those patients in whom excessive thinning-out of the posterior meatal wall was done.