An elevation of plasma vasopressin levels has been frequently observed in Meniere's disease patients. However, little is known regarding the mechanism behind this elevation. The plasma vasopressin levels and plasma osmolality were therefore determined in 18 diagnosed Meniere's disease patients and 20 patients with other types of vertigo, who required admission for severe vertigo attacks. All participants were given questionnaires regarding their clinical and psychological status, including their stress levels and depression status, to evaluate environmental stress events. The plasma vasopressin levels of Meniere's disease patients in the acute phase (4.1 +/- 1.37 pg/ml) were significantly higher compared with with those of other vertigo patients in the acute phase (2.1 +/- 0.41 pg/ml) (P < 0.01). The average plasma osmolality of the Meniere's disease group was higher than that of the other vertigo patients group (P < 0.05). No significant difference in reported stress levels, depression status and prevalence of primary headache between the groups was observed. The plasma vasopressin showed no significant correlation with the patients' clinical data (occurrence of emesis or nausea, prevalence of primary headache, depression status and stress). No correlation between the plasma vasopressin and the plasma osmolarity was observed in the Meniere's disease group. These results suggest that the elevation of plasma vasopressin in the acute phase of Meniere's disease is therefore related to the pathogenesis of Meniere's attacks, and the results obtained may provide helpful information for distinguishing between Meniere's disease and other various inner ear diseases.