It is important to be aware of the potential ototoxicity of any drug, vehicle, or antibiotic that is used in the middle ear. It has been suggested that antiseptic which could trickle into the middle ear through a perforated tympanic membrane during the skin sterilization preceding otosurgery might cause inner ear damage, resulting in deafness. Povidone-iodine solution and povidone-iodine scrub, in combination or separately, are commonly used preoperative antiseptics in the middle ear surgery. The ototoxicity of topically applied povidone-iodine preparation in chinchilla was verified electrophysiologically by Morizono et al (1982), but they did not perform histologic verification of the functional findings because animals were followed only to 24 hours after antiseptic application. In the present study, the ototoxicity of povidone-iodine solution and scrub, when topically applied to the middle ear of the guinea pig, was studied by means of light microscopy. There are total loss of the outer hair cells and vacuolation of the stria vascularis in the basal and second turns of the organ of Corti, but partial loss of the supporting cells in the second turn of the organ of Corti. Conclusively, the ototoxicity of povidone-iodine preparation is verified histologically.