In the study of cochlear function an animal model in which apical outer hair cells could be destroyed with retention of inner hair cells would be valuable. Our object was to attempt to reproduce a reported method in a scientific manner. Behavioural response thresholds to pure tones were recorded in 7 monaural chinchillas. In 5, Kanamycin was administered in ototoxic dosage until the thresholds deteriorated. The other 2 served as controls. Cochlear histology was assessed from embedded surface preparations. In only one of the 5 animals was the aim achieved. In this animal outer hair cells were absent virtually throughout the cochlea and inner hair cell retention was basal. The thresholds were elevated on average 40 dB throughout the frequency range. This is in keeping with current concepts of cochlear function.