Introduction: Auto-mastoidectomy is a rare complication that can develop after chronic middle ear infection and can be seen in cases where no response to classical infection treatment is obtained. Case Report: A 55-year-old male patient applied to the emergency department for a left ear pain complaint. In his examination, he was conscious, but orientation and cooperation were not complete. The brain CT showed a mastoidectomy cavity on the left, but he had never been operated on. Conclusion: The destruction of bones and tissues may cause the current condition in the brain. This case report examines a case of auto-mastoidectomy, which can be diagnosed when the brain abscess develops. References: 1. Lee S, Yeo S, Park M, Byun J. Clinical Analysis of 22 Cases with Automastoidectomy Caused by Cholesteatoma. The Journal of International Advanced Otology 2013; 9(2), 232. 2. Semann MT, Megerian CA. The pathophysiology of cholesteatoma. Otolaryngol Clin N Am 2006;39: 1143-59. 3. Prof. Dr. Çetin Vural. Kolesteatom nedir? Available from: https://www.cetinvural.com/kolesteatom/. Accesed 10.4.22 4. Sun J, Sun J. Intracranial complications of chronic otitis media. European Archives of Oto-Rhino-Laryngology 2014; 271(11), 2923-2926. 5. Song SY, Park DW, Koo JH, Lee SR, Park CK, Hahm CK, et. al. CT findings of automastoidectomy: comparison with postmastoidectomy defect of the temporal bone. Journal of the Korean Radiological Society 1996; 35(4), 447-452.