Congenital cytomegalovirus (CMV) infection is a major public health problem because 30 000 to 40 000 neonates with the infection are born each year in the United States. Although 90% of the congenitally infected infants are asymptomatic at birth, evidence is accumulating that these infants are at risk for audiologic, neurologic, and developmental sequelae. The current study describes the audiologic outcome of 59 infants with asymptomatic congenital CMV infection compared with 26 control infants. Eight of 59 infected infants had congenital sensorineural hearing loss (SNHL) but none of the control subjects did. Longitudinal audiologic assessments revealed that 5 of the 8 infants had further deterioration of their SNHL; a ninth infant with initially normal hearing experienced a unilateral SNHL during the first year of life, with further deterioration subsequently. The frequency of SNHL was similar for infected infants born to mothers with recurrent CMV infections during pregnancy (2 of 9) and for those born to mothers who experienced primary CMV infections (5 of 26). There was a significant difference between the occurrence of hearing loss in infected infants with normal computed tomographic scans (2 of 40) compared with those with either periventricular radiolucencies (4 of 13) or calcifications (1 of 3). Children with SNHL often have no identified cause of the loss; thus, it is likely that many of these children had asymptomatic congenital CMV infection. Given the progressive nature of SNHL associated with asymptomatic congenital CMV infection, longitudinal audiologic assessments are mandatory.