A systematic double-blind assessment of case histories and histopathologic findings in temporal bones in the collection at the Massachusetts Eye and Ear Infirmary was performed to test the hypothesis that clinical Meniere's syndrome is associated with endolymphatic hydrops demonstrated histopathologically at death. Thirteen of 13 cases of clinical Meniere's syndrome were found to have endolymphatic hydrops not attributable to other causes. However, some patients with idiopathic endolymphatic hydrops did not exhibit clinical Meniere's syndrome as revealed in their medical records. These results challenge the dogma that endolymphatic hydrops per se generates the symptoms of Meniere's syndrome.