A variety of topically applied pharmacological agents such as antibiotics, antiseptics and antimycotics are known to cause functional damage to the inner ear end-organs. Interestingly, some of these agents have a different level of effect on the different inner ear end-organs (i.e. cochlea, semicircular canals and otolith organs). In recent years an animal model for assessing the effect of agents applied locally to the middle ear on the inner ear has been developed in our laboratory. This model makes use of auditory brainstem responses (ABR), vestibular evoked potentials (VsEPs) in response to linear acceleration stimuli and VsEPs in response to angular stimuli which reflect the function of the cochlea, otolith organs and semicircular canals respectively. During the last years the effect of gentamicin, povidone-iodine, alcohol, chlorhexidine and hydrogen peroxide on the different end organs has been assessed using this model. It appears that the general pattern of effect is as follows: ABR (cochlea) is the most sensitive to the various pharmacologic agents; angular VsEPs (semi-circular canals) the least sensitive; linear VsEPs (otolith organs) intermediate between them.