Seroconversion to cytomegalovirus occurs in 1%-4% of pregnant women, most of whom are seropositive prior to pregnancy. In 0.2%-2.5% of their newborn infants there is evidence of intrauterine infection; most are born without any clinical findings The typical clinical symptoms of symptomatic congenital CMV are observed in 10-20% of infected neonates. They include intrauterine growth restriction, microcephaly, hepatosplenomegaly, petechiae, jaundice, thrombocytopenia, anemia, chorioretinitis, hearing loss and/or other findings. Long-term neurodevelopmental sequelae include mental retardation, motor impairment, sensorineural hearing loss and/or visual impairment. These may occur even in infants who are free of symptoms at birth. Most infants born with severe neonatal symptoms of congenital CMV are born to mothers with primary infection during pregnancy. However, since about half of the infants infected with CMV in utero, including those with severe neonatal symptoms, are born to mothers with preconceptional immunity, we have to conclude that congenital CMV may be a significant problem even in children born to mothers with pre-pregnancy immunization. This may justify the use of invasive methods for the detection of possible fetal infection even in cases of non-primary CMV infection. This should also be a consideration when deciding upon population screening or immunization for CMV.