We present a case of the Wildervanck (cervico-oculo-acoustic) syndrome exhibiting congenital deafness. Klippel-Feil anomaly and lateral rectus palsy with enophthalmos. Audiometry indicated a predominantly conductive loss which, because of masking difficulties, was assumed to be bilateral: an erroneous assumption supported by results of conventional petrous bone tomography which failed to demonstrate any abnormality of the inner ears. Computed tomography (CT), however, revealed a severe Mondini dysplasia of one ear, a condition which must be assumed to be associated with severe sensorineural hearing loss. Reconstructive middle ear surgery for the conductive loss on the other side was therefore contraindicated.