New bone formation within the cochlea has been found more frequently than expected during cochlear implantation. Although implantation of partially ossified cochleas with long multichannel electrodes is possible, in practicality it may be difficult to determine whether electrode insertion is feasible prior to attempting it. In spite of use of high resolution computerized tomography, the presence, nature, and extent of new bone formation in the scala tympani is often difficult to ascertain. Flexible fiberoptic otologic endoscopes, 0.7 mm and 1.0 mm in diameter, were developed for the purpose of visualizing the fluid-containing scalae of the cochlea. In order to determine the efficacy of the device in visualizing the interior of the cochlea, as well as determining possible damage caused by its use, ten formalin fixed human temporal bones were studied. The flexible fiberoptic otologic endoscope was found to be capable of passage through the scala tympani of the cochlea in the inferior segment and of identifying normal and abnormal structures. Passage beyond this point resulted in damage to the spiral ligament. We conclude that human trials of use of the endoscope during cochlear implantation on previously deafened individuals is feasible.