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Objectives: The close anatomic relationship between the cochlea and the labyrinthine segment of the facial nerve represent both a potential hazard during cochlear implantation. The purpose of this study was to identify the prevalence of cochlear-facial dehiscence (CFD) in the CT scan. Materials and methods: Retrospective analysis for temporal bone CT with the same collimation was performed in 57 patients to evaluate the relationship of the cochlea and the labyrinthine segment of facial nerve canal. The nearest distance between basal turn of cochlea and labyrinthine segment of fallopian canal for all of axial, coronal, Stenver, and Poschl planes were measured using Hounsfield unit value and electronic calipers. Results: Total 10 of 90 ears (11.1%) were found to be a cochlear-facial dehiscence one of four planes: 3 (3.33%) for axial; 3 (3.33%) for coronal; 8 (8.89%) for Stenver; 2 (2.22%) for Poschl plane. None of the ears appeared to have dehiscence on all four planes. The length of CFD ranged from 0.1 to 0.6 mm (0.356 ± 0.15 mm). Conclusion: The radiologic prevalence of CFD was 11.1%, which was much higher than the histologic prevalence of 0.6%, but it was similar to the rate of facial nerve stimulation following the cochlear implantation. [ABSTRACT FROM AUTHOR]