Congenital cytomegalovirus (CMV) infection is the leading non-genetic cause of sensorineural hearing loss (SNHL) in children in the United States, and is the most frequent known viral cause of mental disability. Approximately one percent of all newborn infants in the United States are infected with CMV. Of those infected, approximately 10% have involvement that is evident at birth (symptomatic congenital CMV disease) with manifestations including microcephaly, central nervous system abnormalities, chorioretinitis, hepatosplenomegaly, and SNHL. The most common sequelae following congenital CMV infection is SNHL and it occurs in up to 50% of infants with symptomatic congenital CMV infection and in 15% of asymptomatic infants. Overall, congenital CMV infection accounts for one-third of all cases of SNHL. Among newborn infants who fail hearing screening, the prevalence of congenital CMV infection is much higher (six to 10%) than the general newborn population (<1%). Since early therapeutic intervention for infants with symptomatic congenital CMV infections improves audiological and neurodevelopmental outcomes early diagnosis is essential for early treatment and maximizing infant outcomes.