Describing the course of illness of six newborn infants suffering from connatal respectively postnatal acquired cytomegalovirus infection most important problems of this disease during neonatal period are discussed. There are reviewed: questions according diagnostic specificity of CMV-infection in the newborn; neurologic and sensorineural sequelae; the influence of prematurity and immune deficiency on the severity of the disease; possibility of chemotherapy against CMV and; the morbidity of preterm infants following postnatal, especially transfusion-associated CMV-infection.