Recently there has been considerable investigation into the relationship of the immune system and immune disorder to Meniere's disease. Immunoglobulin G (IgG) antibody and complement are both present in endolymphatic fluid and it is possible that endolymphatic hydrops is due to immune complex. The authors' results show that patients with endolymphatic hydrops had elevated levels of circulating immune complex (CIC) of IgG (24.80 μg/mL). The levels of functional complement activity (CH50) were significantly lower in patients (249.7 HU) than in controls. Circulating levels of CIC and CH50 were positively correlated. Immunoglobulin G, immunoglobulin M (IgM), and subpopulation of B lymphocytes were elevated, but there was no alteration in subpopulations of T-helper, T-suppressor, and natural killer (NK) cells in peripheral blood.