This is a report of the inner ear pathology found in a pair of temporal bones from a deaf mutism case. This patient's spouse and four of six children were deaf mutes. Some members in the succeeding generation were also known to be deaf mutes. The temporal bones (horizontally sectioned) showed the cochleo-saccular degeneration with exactly similar extent bilaterally. The scala media and the saccular space were atrophied, and displaced membranes were attached onto the degenerated sensory epithelia in many areas, but some portion of the scala media exhibited an ectatic view. The cochlear and saccular nerves were severely reduced. In addition to the pathology found in the pars inferior, the internal auditory canal and the cochlear aqueduct were enlarged. All end organs and nerves in the pars superior were intact.