This study presents animal experiments on endotoxin (lipopolysaccharides: LPS) damage to the inner ear with special reference to the stria vascularis. The experimental group animals (albino guinea pigs) were injected with LPS into the perilymphatic space. Pyrogen-free saline (PFS) was injected into the control group. Strial structural evaluation and hearing tests were carried out before and one, three and five days after treatment. In PFS-treated (control) ears, no significant change was found either in hearing or structure. However, thresholds of N1/P1 were elevated and latencies prolonged in LPS-treated ears. They had severe strial damage mainly to the cellular organelles. The mitochondria became swollen with a disordered, broken, degenerated or absent crest. Secondary lysosomes and autophagosomes increased in number with the presence of medulative inclusions. Na(+)-K(+)-ATPase reactant was obviously diminished. It is concluded that LPS-induced strial ototoxicity produces ion imbalance, causing changes in endolymph composition and energy failure in the organ of Corti and is also responsible for the pathogenesis of inner ear sequelae secondary to otitis media.