Results of an oto-neurological study comprising 69 diabetics are reported. An inner-ear lesion was found in 28 cases, characterized as a rule by progressing, symmetric hearing loss of the perceptive type. A few patients reported acute onset of hearing loss, accompanied by tinnitus and dizziness. In cases where recruitment tests could be carried out, the disease was found to be located in the cochlea. Vestibular function tests did not reveal involvement of the vestibular part of the labyrinth. One of the patients had peripheral facial palsy. A correlation was found between the inner-ear lesion and the late diabetic complications as indicated by the degree of retinopathy. Hearing loss was commoner in elderly than in younger diabetics. The pathogenesis is assumed to be angiopathy affecting the blood vessels of the labyrinth or acoustic nerve, similar to that which may be found in other late complications of diabetes.