Postmortem blood cultures were taken from 105 neonates dying at Harare Hospital during a 1-year period. The infants were characterized by prematurity (63% < 37 weeks gestation), low birth weight (60% < 2500 g) and low Apgar score at 1 min (43% < 3). More than one-half of the infants died within 48 hours of admission. Positive blood cultures within 10 minutes of death occurred in 44% of infants, and Klebsiella sp. were by far the most common isolates. Positive blood cultures were associated with very low birth weight (< 1500 g), and with babies who survived for > 48 hours. Antibodies to human immunodeficiency virus type 1 were found in 40% of the infants, and a high proportion of these had Klebsiella bacteremia. Nearly all the infants had received antibiotic therapy, usually penicillin and gentamicin. Very few babies who had received a cephalosporin had a positive blood culture, and in vitro tests showed that although many organisms were resistant to penicillin and the aminoglycosides, very few showed resistance to the cephalosporins. Our findings suggest that cephalosporins may be useful in treating severe neonatal sepsis, particularly when there is no response to more standard therapy.