Objective. The study sought to determine the relationship between cytomegalovirus (CMV) viremia during early infancy and clinical and laboratory outcome events, particularly hearing loss in infants with symptomatic congenital CMV infection involving the central nervous system (CNS). Study design. A total of 147 infant patients were enrolled prospectively in 2 clinical trials evaluating ganciclovir for the treatment of symptomatic congenital CMV infection involving the CNS. Aliquots of serum collected at enrollment in either of the 2 trials were available from 50 of the infants, and the degree of viremia was determined by real-time quantitative polymerase chain reaction. Results. Of the 50 infants from whom serum samples were available, 37 had detectable CMV DNA in the serum sample collected at enrollment and were classified as viremic. Viremic infants were more likely to have (1) hearing loss both at enrollment (P = .045) and at the 6-month follow-up testing (P = .035) and (2) other indicators of active CMV disease, including elevated levels of alanine aminotransferase, petechial rash, and organomegaly. Conclusion. In children with symptomatic congenital CMV infection involving the CNS, viremia during early infancy is associated with hearing loss and systemic CMV disease.