The incidence of postnatal human cytomegalovirus (HCMV) reactivation during lactation equals the maternal seroprevalence. Infectious virus, viral DNA and RNA can be isolated from cells and fat free milk whey. Early onset of viral DNAlactia and virolactia as well as high viral load in milk whey are maternal risk factors for virus transmission. Preterm infants below 1000 g birthweight and a gestational age below 30 weeks may be at high risk of acquiring a symptomatic HCMV infection. Several recent studies using frozen milk for feeding describe low transmission rates and mostly asymptomatically infected neonates. However despite different freeze-storing procedures HCMV transmission occurred and severe HCMV infections were observed. Only few data exist on the long-term outcome of postnatally acquired HCMV infection via breast milk. Additional long-term outcome studies are needed. The newly developed short-term pasteurisation may be a reliable alternative to freezing and Holder pasteurisation, since important milk constituents are conserved.