Background: Congenital cytomegalovirus (cCMV) is the most common non-genetic cause of childhood sensorineural hearing loss. Antiviral treatment has been shown to prevent hearing deterioration in these infants. However, studies focused on infants with hearing impairment at birth and on the specific degree of impairment and further improvement or deterioration are lacking. Objective: To investigate the relationship between hearing status at birth and any change in hearing status at the end of a prolonged follow-up period, after receiving 12 months of antiviral treatment in children born with hearing impairment due to congenital cCMV. Methods: Clinical, laboratory, radiological and audiological data of all infants with cCMV infection followed in our centre between 2005 and 2013 were reviewed. Treatment with antiviral medication for hearing impairment found during the neonatal period was12 months of gan/valganciclovir. Hearing studies were performed only on infants who had been followed up for more than 1 year after treatment. Results Hearing impairment at birth was found in 54 (36.2%) of the 149 infants diagnosed with symptomatic cCMV, and found in 77 affected ears; unilateral in 31 (57.4%) and bilateral in 23 (42.6%). After 1 year of antiviral treatment and a long-term follow-up of the 77 affected ears at baseline, 50 (64.9%) had improved, 22 (28.6%) remained unchanged and 5 (6.5%) had deteriorated. Most improved ears (38/50=76%) returned to normal hearing. Improvement was most likely to occur in infants born with mild or moderate hearing loss and less in those with severe impairment. Conclusions: We found that infants born with cCMV and hearing impairment, receiving 12 months of antiviral treatment, showed significant improvement in hearing status. The probability of hearing improvement seems inversely related to the severity of the impairment at birth.