The incidence of nonvisualization of the vestibular aqueduct and the endolymphatic duct-endolymphatic sac (ED-ES) complex as well as the type of periaqueductal pneumatization were evaluated in 23 patients with definite Meniere's disease (MD) by high-resolution CT and by MRI. Fifty subjects with no previous history of any ear disease were used as a control group. High-resolution CT results disclosed that in the control group the percentage of nonvisualized vestibular aqueduct (3.4%) was statistically significantly lower than in the MD group, when either the diseased ear (27.8%) or the nondiseased ear of the same group (22.2%) was examined. In addition, no differences were observed between the diseased and nondiseased ears of the patients with MD. The periaqueductal pneumatization was also found to be statistically significantly lower in the MD group. As regards the MRI examination, the results of the analysis showed that the ED-ES complex was visualized more frequently in the ears of the control subjects (64.1%) than in the diseased ears of the patients with Meniere's disease (39.1%). This difference had a marginal statistical significance (P approximately 0.05). We discussed the results in relation to possible underlying pathophysiologic mechanisms involving the flow of endolymph toward the ES during the different stages of the disease.