In the Netherlands all neonates are routinely screened for hearing during the first weeks after birth with the Otoacoustic Emissions (OAE) procedure. After the second refer an Automated Auditory Brainstem Response (AABR) is performed. The parents of all newborns, born at ≥ 37 weeks gestational age, that fail this AABR in the Netherlands (about 550 yearly) will be asked for consent for CMV-testing on the dried blood spots. Newborns diagnosed with congenital CMV and with confirmed SNHL (≥ 20 dB) are eligible for inclusion. After informed consent infants will be offered treatment before the age of 13 weeks (6 weeks valganciclovir 32 mg/kg daily dose; oral solution). Parents may decide to participate in the trial in the control group (no antiviral treatment). Infants will be monitored for leucopenia and liver- and kidney function. Inclusion will continue for at least 1.5 years, or until at least 40 infants have been included in the trial.