In 1978 353 premature and mature newborns were admitted to our neonatal and intensive care unit. 34 children developed bacterial infections. B-streptococci were the offending organisms in 6 cases, pneumococci in 1 case, 5 of these 7 infections were of the early-onset type, 2 of the late-onset type. The early-onset type disease manifests itself by respiratory distress and shock. It is transmitted vertically from mother to child before or during birth. 3 of our 5 affected children died. The late-onset type disease occurs after 5-10 days, is transmitted as horizontal, mostly nosocomial infection, and presents as sepsis with meningitis or - as in one of our cases - with osteomyelitis. In addition to the 7 sick infants 8 of the 353 admitted newborns were colonized without signs of disease. Early diagnosis, therapy, and prophylaxis of these infections present still unsolved problems.