We describe a patient with a polyethylene tube to the middle ear who developed severe deafness and vertigo after treatment with ear drops where neomycin B was considered to be the most likely offending agent. High concentration of this antibiotic in the ear drops and access of the solution to the round window membrane in the absence of inflammatory edema and secretion may have been significant factors contributing to this serious side effect. Less ototoxic preparations should be used in patients with perforated tympanic membranes or grommets.