Kanamycin ototoxicity, combined with behavioral audiometry to evaluate threshold shifts, was used to destroy outer hair cells (OHCs) in the basal cochlea of the chincilla while leaving the inner hair cell (IHC) population largely intact. After survival times of four weeks to one year, transmission electron microscopy was employed to determine the condition of surviving hair cells and neural elements. Throughout the region of OHC loss, IHCs and their innervation were normal in appearance if their adjacent supporting cells were undamaged. When IHC supporting cells, specifically the inner pillar cells, were damaged or absent, damage to IHCs was commonly observed. Such supporting cell-related damage included extrusion of the cuticular plate from the surface of the reticular lamina, encapsulation and/or fusion of stereocilia, and gross distortion of hair cell shape. When the outer supporting cells of the organ of Corti were undamaged following OHC loss, outer spiral fibers were found to have survived in near-normal numbers in the region from 0.5-1.0 mm basal to the basal most surviving OHC, but suffered progressive attrition toward the basal end of the cochlea. It is concluded that kanamycin-induced OHC loss can occur without concommitant IHC damage or outer spiral fiber loss.