목적: BOR/BO syndrome is one of the most common forms of autosomal dominant syndromic hearing loss. So, we analyzed the temporal bone CT findings in BOR/BO patients and tried to find possible causes of conductive component and sensorineural component of hearing loss 방법:A retrospective chart and CT images were reviewed in non-familial BOR/BO patients. Twenty-two patients(44 ears) who diagnosed with typical or atypical BOR/BO syndrome at Yonsei Unversity Severance Hospital were included. We analyzed pure tone audiometry and temporal bone CT findings and tried to assess association between hearing loss pattern and temporal bone CT findings 결과:Average air conduction hearing level was 70.82dBHL and average air bone gap was 29.41dBHL. In the severe air conduction hearing loss group, 67%(14/21) of ears have ossicular anomaly, there are no significant difference compare with non-severe group(70%, 16/23). Cochlea anomaly was revealed in 62%(13/21) of ears in severe group and 48%(11/23) of ears in non-severe group. Severe group has 67% of prevalence and non-severe group has 48% of prevalence in vestibular aqueduct enlargement. In the aspect of AB gap, 74%(17/23) of ears in over average AB gap group have ossicular anomaly and 67%(14/21) of under average group have ossicular anomaly. Cochlea anomaly was revealed in 57%(13/23) of ears in over average AB gap group and 52%(11/21) of ears in under average group. Over average group has 65%(15/23) of prevalence in vestibular aqueduct enalrgement and under average group has 48%(10/21) of prevalence. Facial nerve anomaly was revealed in 73%(32/44) of ears and facial nerve overhanging on the oval window was found in 11 ears. 결론:In the hearing pattern of BOR/BO syndrome, primary cause of air bone gap difference resulted from ossicular anomaly and sensorineural component resulted from cochlea anomaly. In some case of ears, overhanging facial nerve on the oval window can makes difficult to do stapes surgery.