Cytomegalovirus (CMV) is the most common congenital infection in humans. Congenital CMV infection can follow either a primary or recurrent maternal infection, but the likelihood of fetal infection and the risk of associated damage is higher after a primary infection. Approximately 90% of congenitally infected infants are asymptomatic at birth. Jaundice, petechiae, and hepatosplenomegaly are the most frequently noted clinical triad in symptomatic infants. More frequent and more severe sequelae occur in symptomatic infants, notably psychomotor hearing loss and retardation. Congenital CMV infection can be diagnosed by isolation of the virus from the urine or saliva within the first three weeks of life. Rapid diagnosis can be accomplished by detection of CMV DNA by DNA amplification or hybridization techniques.