Lateral polytomography of the vestibular aqueduct by computed radiography was carried out in 30 normal subjects and 25 patients with Meniere's disease, 14 of whom had bilateral involvement. The vestibular aqueduct could be identified clearly not only in normal subjects but also in patients with Menière's disease. Normal vestibular aqueducts were funnel-shaped or tubular, and the width of the external aperture was 6.0 mm on average. In contrast, a hypoplastic vestibular aqueduct with a narrow external aperture was often observed in patients with Menière's disease. Especially, in affected ears of patients with unilateral Menière's disease, the external aperture was very narrow; its mean width was 2.2 mm. In these cases, the most common radiographic configuration of the vestibular aqueduct was filiform. Meanwhile bilateral Menière's disease had a relatively wide external aperture compared with that of unilateral Menière's disease, although a hypoplastic vestibular aqueduct was also observed in patients with bilateral Menière's disease. As to the distribution of radiographic configuration types, bilateral Menière's disease had almost the same distribution as in normal ears. From these results, it was concluded that a hypoplastic development of the vestibular aqueduct was based on the etiology of Menière's disease, but general factors as well as a hypoplastic vestibular aqueduct seem to be responsible for bilateral involvement.