The overall goal of this study is to determine the clinical benefit and safety of antiviral therapy for asymptomatic congenital cytomegalovirus (cCMV) infected hearing-impaired infants. We will conduct a multi-center double-blind randomized placebo-controlled trial to determine whether hearing-impaired infants with asymptomatic cCMV have better hearing and language outcomes if they receive valganciclovir antiviral treatment. We will also determine the safety of antiviral valganciclovir therapy for asymptomatic cCMV-infected hearing impaired infants. This study will be unique in that the cohort enrolled will only include hearing-impaired infants with asymptomatic cCMV. Primary Objective: To determine if treatment of cCMV-infected hearing impaired infants with isolated hearing loss with the antiviral drug valganciclovir reduces the mean slope of total hearing thresholds over the 20 months after randomization compared to untreated cCMV-infected infants with isolated hearing loss. Main Secondary Objectives: 1. To determine if valganciclovir treatment improves the following outcomes when compared to the control group: 1. The slope of best ear hearing thresholds over the 20 months after randomization. 2. The MacArthur-Bates Communicative Development Inventory (CDI) percentile score for words produced at 20 months of age. 2. To evaluate safety measures based on all grade 3 or greater new adverse events designated by the NIAID Division of AIDS (DAIDS) toxicity tables.