Introduction: Ototoxicity is a health problem appearing after powerful treatments in serioushealth conditions. It is sometimes inevitable when treatment of the serious disease is required.Cisplatin is an antineoplastic agent which was investigated previously to reveal increasednitrogen and reactive oxygen radicals that damages hair cells, resulting in ototoxicity. N-acetylcysteine, previously shown to decrease ototoxicity caused by different agents, is knownto be a powerful in vitro antioxidant. Probably N-acetylcysteine, in addition to its antioxidanteffect, blocks a cascade where reactive oxygen species result in apoptosis in the cochlea.Objectives: The possible preventive effect of N-acetylcysteine in cisplatin ototoxicity wasstudied with auditory brain stem responses, otoacoustic emissions, and histopathological inves-tigation of the cochlea in a scanning electron microscopy.Methods: This study was conducted on 21 Wistar Albino rats in four groups. 1 mL/kg/day threetimes in total intraperitoneal (i.p.) Saline (n = 5), 500 mg/kg/day i.p. three times in totalN-acetylcysteine (n = 5), i.p. 15 mg/kg cisplatin alone (single dose) (n = 5) and i.p. 15 mg/kgcisplatin plus 500 mg/kg/day N-acetylcysteine (n = 6) were administered. The rats were anes-thetized to study the hearing tests before and after the experiment. The rats were sacrificedto investigate the cochleas by scanning electron microscopy.