This report reviews 12 cases of congenital cholesteatoma of the middle ear, mastoid, and petrous pyramid seen mostly in adult and older juvenile patients between 1984 and 1992. Featured herein are two unique instances of purulent discharge external to an intact tympanic membrane via a fistula caused by extensive mastoidal erosion, three cases that illustrate the importance in Oriental populations of the use of high resolution computed tomography to obviate misdiagnosis when all other diagnostic techniques suggest unilateral otosclerosis, and two instances of multicentric cholestea-tomas in well-separated portions of the same temporal bone associated with ossicular anomalies of possible congenital origin. The predilective sites and extent of involvement in this series reinforces the pattern for this age group noted by others. That is, although most of the lesions were too diffusely invasive to define possible formative sites, those that were relatively small and discretely located were found at locations other than the anterior tympanum. This would suggest that their sites of origin and pathogeneses may be different from those commonly found in the anterosuperior tympanum of very young children.