Nowadays, in severe infections during the neonatal period new bacteria--group B streptococci--have to be taken into account, since in some clinics they already predominate over gramnegative rods. Septicemia and meningitis may be caused by group B streptococci. The septicemia which especially threatents prematures starts with apnoeic spells in the very first hours after birth and may be easily misdiagnosed as an idiopathic respiratory distress syndrome. The mortality is very high (about 60%). Meningitis starts later, normally during the 3rd to 4th week. Seizures are typical at the onset. Group B streptococci may be identified in the CSF by counterimmunoelectrophoresis within one hour. The prognosis is more favourable in meningitis than in septicemia (mortality about 20%). Survivors have little neurological sequelae. Penicillin G or ampicillin combination with an aminoglycoside is recommended as chemotherapy. Exchange transfusion should be considered early. Group B streptococci causing the septic form may be transfered during labour since up to 25% of pregnant women are colonized. Nosocomial transmission of group B streptococci may be the reason for meningitis. Prophylactic penicillin does not seem to help in preventing the disease, but it is possible, that meningitis of the newborn may be prevented by immunizing the mother during pregnancy.