Viral infection is the most frequent cause of unilateral acute peripheral vestibulopathy (APV). Another possible cause is a vascular disorder in the labyrinth area associated with alterations in hemostasis. In a group of 45 patients with APV and in a series of 25 patients with Ménière's disease (control group), we evaluated blood parameters, including total cholesterol, triglycerides, apolipoprotein A and B, lipoprotein (a), homocysteine, folate, prothrombin time, activated partial thromboplastin time. D-dimer, fibrinogen, antithrombin III, protein C, protein S, activated protein C resistance, and anticardiolipin antibodies. In the acute phase of their disease, the patients with APV exhibited increased plasma levels of fibrinogen (341.5 +/- 136.8 standard deviation [SD] versus 268.1 +/- 72.6 SD mg/dl; p = .05); increased plasma levels of D-dimer (305 +/- 158 SD versus 201 +/- 106 SD ng/dl; p = .008); enhanced plasma levels of lipoprotein (a) (42.6 +/- 38.5 SD versus 16.9 +/- 17.7 SD mg/dl; F = 5.67, p = .02); high leukocyte count (9.2 +/- 2.7 SD versus 6.4 +/- 1.2 SD x 10(3)/microliter; F = 8.42, p < .006); and low serum folate concentration (5.1 +/- 1.7 SD versus 7.2 +/- 2.6 SD ng/ml; F = 4.34, p = .04). During follow-up, the prothrombin time was prolonged (p = .04), and leukocyte count was decreased (p < .019) in the patients with APV, whereas fibrinogen, D-dimer, lipoprotein (a), and folate were unchanged. In this study, we demonstrated that patients with APV exhibit significant involvement of the hemostatic system.