Using a computer-aided three-dimensional reconstruction and measurement method, 12 measurements were made to determine the dimensions of the maculae, cristae ampullares, and semicircular canals in 18 temporal bones from nine pairs of age-matched male and female individuals (1 day to 76 years old). The surface areas of the utricular and saccular maculae were significantly larger in male than in female specimens (two-way analysis of variance, F = 9.00, df = 1, p less than 0.01; F = 4.57, df = 1, p less than 0.05, respectively). The width of the utricular macula and the length of the saccular macula were also significantly greater in male than in female specimens (two-way analysis of variance, F = 5.17, df = 1, p less than 0.05; F = 4.33, df = 1, p less than 0.05, respectively). Finally, the three semicircular canals were larger in diameter in male vs. female specimens; this difference was statistically significant for the superior semicircular canal (two-way analysis of variance, F = 10.74, df = 1, p less than 0.01). By contrast, none of these dimensions of those vestibular structures showed any significant change in size with advancing postnatal age. We propose from these findings that there appears to be sexual dimorphism in the vestibular apparatus.