The role of transforming growth factor-beta(TGF-β) during the development of immune labyrinthitis was investigated. The levels of TGF-β1 in the perilymph and blood was assessed using enzyme-linked immunosorbent assay(ELISA) after keyhole limpet hemocyanin(KLH) was infused into the scala tympani of the rat cochleas following systemic immunization. The levels of TGF-β1 in the perilymph was highest at 12 hours following inner ear(IE) challenge and decresead at 24 hours while the levels of TGF-B1 in the serum was highest at 3 day and decreased through 2 weeks following IE challenge. The results suggest that TGF-β1 may be released in the beginning of inflammation and play a role of immunoregulator in the pathogenesis of immune labyrinthitis.