Three cases of congenital cytomegalovirus (CMV) infection with long-term audiovestibular sequelae are presented. Case 1 had no hearing in one ear and severe progressive hearing loss in the other ear; he showed vestibular symptoms at the age of 4.5 years. Case 2 had severe but stationary hearing loss in one ear and showed hearing impairment symptoms in the other ear at 9-13 years of age. Case 3 did not have hearing impairment symptoms, or vestibular symptoms, but was found to have severe progressive hearing loss from the age of 15 months onwards, which led to profound deafness at the age of 2 years and vestibular areflexia at or before the age of 4 years. These cases may represent 3 symptomatically different types of delayed endolabyrinthine hydrops. Type 1 (ipsilateral hydrops) incorporates vestibular symptoms only because of a lack of hearing in the offending labyrinth. Type 2 (contralateral hydrops) incorporates hearing impairment symptoms only because of a lack of vestibular function on both sides and type 3 does not incorporate hearing impairment symptoms or vestibular symptoms (other than those relating to a complete lack of function). Given the present findings, those described by Weiss and Ronis (Trans. Pa. Acad. Opthalmol. Otolaryngol., 30 (1977) 52-54) in one case and other reported findings relating to histopathological or imaging methods in somewhat similar cases, it seems appropriate to include congenital CMV infection in the differential diagnosis of delayed endolymphatic hydrops.