Perinatal infections with Streptococcus pneumoniae although rare, have caused morbidity and mortality in both neonatal and puerperal patients. To determine the incidence of proven pneumococcal sepsis in these patient groups, blood culture records from 1977 to 1989 were reviewed. Of 89 parturient patients with true positive blood cultures, two (2.2%) were positive for the pneumococcus, whereas of 240 infants with positive blood cultures, three (1.25%) grew pneumococcus. The incidence of maternal pneumococcal sepsis was 0.04/1000 live births, and that of the neonates, 0.06/1000, and the overall rate for sepsis in these two groups was 1.7 and 4.7/1000 live births, respectively. In three mother-infant pairs, the identical pneumococcal serotypes, 7, 18, and 23, were isolated from both mother and infant. Birthweights and gestational ages of the infants ranged from 2330 to 3730 gm and 34 to 40 weeks, respectively. Respiratory distress and poor peripheral perfusion were the predominant clinical signs in the infants with sepsis and became apparent from shortly after birth until 5 days of life. Pyrexia, poor general condition, and leukocytosis characterized the mothers with sepsis. All patients survived following antibiotic and supportive care. Our epidemiologic survey confirms the rareness of perinatal pneumococcal infection and the ability of these organisms to cause morbidity in both mothers and infants.