It has been reported in rats and humans that the renal damage induced by aminoglycoside antibiotics is reduced by Fosfomycin (FOM). In the present study, it was investigated whether or not the aminoglycoside ototoxic effect is reduced by the combined administration of FOM. The aminoglycoside antibiotics used in this study were kanamycin (KM) and dibekacin (DKB), while rabbits and rats were used as the experimental animals. A protective effect of inner ear damage was not observed in combination with FOM, whereas evident effect for reducing the renal damage was observed, especially in rats. As the concentrations of DKB in serum and perilymph were remarkably decreased by the combined administration of FOM, it could be assumed that the combined use of FOM could possibly reduce the inner ear damage too. The decrease of antibiotic concentration may be attributed to the inhibition to the accumulation of DKB by FOM or to the acceleration of DKB excretion from the kidneys by FOM.