Mastoid obliteration is commonly performed to reduce the size of mastoidectomy cavity following canal wall-down tympanomastoidectomy for chronic otitis media. The indications and techniques for mastoid obliteration as well as total tympanomastoid obliteration will be reviewed. The vast majority of obliteration techniques consist of either local flaps or free grafts (bone, cartilage, fat, hydroxyapatite). The radiographic and histopathologic features of mastoid obliteration will also be reviewed.