Cytomegalovirus (CMV) infection is currently reported as the most common cause of congenital viral induced deafness. However, few systematic studies of the audiovestibular sequelae of this infection are present in the literature. A clinical pathologic study was conducted from 1976 to 1982 to evaluate this. Fifty-two pairs of infant and children's temporal bone studied demonstrated no evidence of CMV endolabyrinthitis even in the single case with evidence of extensive congenital CMV infection. Over 2,000 umbilical cord sera were screened to detect asymptomatic CMV infection with an incidence of 0.38% (and slightly greater than 1% when extrapolated to correct for the sensitivity of the method of detection) in a central Pennsylvania study population. No sensorineural abnormalities were detected in five asymptomatic children and 30 control children. However, three out of six (50%) infants, symptomatic at birth and followed to a mean age of 5.5 years, showed significant and progressive sensorineural loss and vestibular deficits.