Introduction:The foramen of Huschke (FH) is a developmental bone defect located anteroinferior to the external auditory canal. In this study, the frequency of FH and the presence of TMJ herniation into the external auditory canal were investigated using high-resolution computed tomography (HRCT) of the temporal bone in patients with FH. In addition, it was aimed to determine whether there is a relationship between the degree of mastoid pneumatization and mastoid volume and the presence of FH.Materials and Methods:The HRCT images of 352 patients were retrospectively evaluated for the presence of FH and TMJ herniation into the external auditory canal. The degree of pneumatization was determined in 50 patients with FH and 53 patients without FH, and the mastoid volume was measured.Results:Of the 704 temporal bones, 50 (7.1%) were detected to have FH 16 (4.5%) on the right and 34 (9.7%) on the left. The incidence of FH was higher in women on the right than in men (p<0.01). There was strong correlation between the FH width and age for the left side (r=0.466, p<0.01). The mastoid volume was 3.2-15.9 cm3 in the patients with FH and 3.2-16.2 cm3 in those without FH. The degree of pneumatization and mastoid volume did not significantly differ between the both groups (p>0.05). TMJ herniation into the external auditory canal was detected in one of the patients with FH.Conclusions:We could not find a relationship between mastoid bone pneumatization and FH development. The presence of FH should be detected before TMJ and ear surgeries to prevent possible complications.