The longterm prognosis of neonatal septicemia during the first four weeks of life has been estimated. Of 90 infants with the diagnosis of neonatal septicemia during a five-year period, 1969--1973, 65 infants survived the initial treatment. Another two infants died with complications of their main disease, intestinal atresia, at the age of two months. Thus the total mortality in neonatal septicemia in this series was 30%. The remaining 63 children have been investigated between ages of 2 1/2 and 6 1/2 years. Of these 63 children we have found 14 children (22% of the surviving) with handicaps where the septicemia can be regarded as a possible cause of the handicap. Of these 14 children only six had an "uncomplicated" septicemia while four of them had meningitis and four had osteomyelitis. Furthermore, of the 14 handicapped children nine were delivered preterm (28--36 weeks) and all of them had one or more additional neonatal diagnoses than septicemia. The prognosis, both immediate and longterm, of neonatal septicemia in the present series compares favourably to most international studies. The importance of early detection together with an aggresive treatment of the septicemia is stressed and is considered as the main reason for the good prognosis.