In this study, we have discussed the facial canal dehiscence rates in patients with scutum defect, who had undergone surgery with the diagnosis of chronic otitis media with or without cholesteatoma. The operation records of 154 patients who had undergone tympanomastoidectomy with the diagnosis of chronic otitis media with or without cholesteatoma were retrospectively analyzed. Scutum defect was investigated by inspection under direct high magnification following tympanomeatal flap elevation during the operation. Facial canal dehiscence was evaluated by inspection and through palpation by blunt picking after the pathological tissues had been removed. The rate of scutum defect was determined as 29.22% (45 out of 154 patients), and the rate of facial canal dehiscence was determined as 22.07% (34 out of 154 patients). While facial canal dehiscence was encountered in 55.55% of the patients with scutum defect, this rate was determined as 8.25% in patients without scutum defect. While the tympanic segment was the most commonly affected segment of the facial canal, isolated mastoid segment involvement was encountered in only 1 (2.94%) patient. The presence of scutum defect is a significant finding for the prediction of the extent of the disease and facial canal dehiscence. Thus, the surgeon should pay more attention to avoid facial nerve injury during the operation in the patient in whom a scutum defect is detected.