The aim of the research was the comparative analysis of ototoxicity of amikacin and netromycin after their introduction to immature animals in therapeutic doses. As a result according to the registration of distortion-product otoacoustic emission and the record of short-latency auditory brainstem response more expressed toxic action of amikacin was revealed which was reflected in more substantial increase of thresholds of the 1st peak and greater decrease of its amplitude in comparison with the group of the animals receiving netromycin. Introduction of amikacin and netromycin took the same damaging effect on the area of outer hair cells responsible for the perception of frequencies 2 and 4 kHz.