Between 1995 and 2003, we encountered 13 cases of congenital cholesteatoma, among which 5 were opentype. Most of congenital cholesteatoma belong to the closed-type while only a fewcases of the open-type have been reported. Of these 5, one was a mixed form where the open- and closed-types co-existed. All the others were found in adults (mean age, 21.6 years). The mean age of those with the closed-type found during the same period was 8.9 years, indicating that the age at the initial diagnosis was higher for those patients with the open-type. The major complaint of those with open-type cholesteatoma was hearing impairment, asymptom that has been experienced by all and recognized by the patients or others from early childhood. At the initial diagnosis, a conductive deafness of 32.5 to 52.5dB was recognized. In only 2 patients, was a white mass observed through the tympanic membrane, indicating a tendency toward a scarcity of characteristic findings related to this membrane. Four patients had a history of acute otitis media. In 3 of the 5 patients, the development ofmastoid cells was satisfactory on the affected side. Both air content and development of air cells were suppressed in 2, which were suspected to be the effects of otitis media suffered in early childhood. During surgery, cholesteatoma was recognized at the tympanic isthmus and the long process of the incus was absent in all. Three were also devoid of the suprastructure of the stapes. There was no complication of ossicular anomaly. The cholesteatoma, limited to the tympanic isthmus in only one patient, had extended to the attic and mastoid antrum in the others. Revision surgery has been conducted in 3, a remnant of the cholesteatoma appeared pearly in 1 and membranous in the other 2. In many instances, open-type cholesteatoma is invaded extensively by the epithelium, making extirpation difficult.