THE FOLLOWING case is reported because otologists, to whom patients with osteoma of the mastoid come, rarely encounter the condition. It is hoped that the removal technique to be described may be of help to anyone else confronting his first case with the limited skill I possessed. Report of Case A 26-year-old white woman had undergone mastoidectomy on the right, at the age of 8 years, at the Osteopathic Hospital, in Philadelphia. Six years ago, she first noted a bony prominence behind the right mastoid region. The mass had increased in size until it was 2 cm. in diameter and about 12 mm. high; it was hemispherical and smooth on the surface. There were no symptoms. The mastoidectomy scar was somewhat depressed, and the tympanic membrane showed no pathology. X-ray report demonstrated that the osteoma extended through the tables of the skull to the dura. At operation, under ether, May