Autoimmune inner ear diseases have been recognized recently, but the mechanism of hearing loss is still unclear. This study was aimed to induce immunological inflammation in cochlea to establish a model and to examine an effect of prednisolone on the induction. Lewis rats were immunized with normal rabbit IgG in complete Freun's adjuvant, and then injected intravenously with rabbit anti-rat glomerular basement membrane (GBM) antibody twice (anti-GBM Ab group). The binding of anti-GBM antibody and inflammatory cell infiltration in the cochlear plexus were investigated using immunofluorescence microscopy. Immunofluorescence microscopic examination revealed specific binding of anti-GBM Ab to basement membrane of capillaries in the cochlear plexus. Compared to normal rats injected with saline, larger numbers of infiltrated CD4-positive T cells (p < 0.01) and monocytes/macrophages (p < 0.01) were observed. Furthermore, prednisolone suppressed the infiltration of CD4-positive cells (p < 0.05) and monocytes/macrophages (p < 0.01). These results suggest that an inflammatory reaction was induced by binding of anti-basement membrane antibody to cochlear capillaries in inner ear and that this inflammation in cochlea could be reduced by prednisolone.