This study analyzed the clinical characteristics of 69 neonates who were admitted to the University of Minnesota Hospital between January, 1972, and June, 1984, with early onset Group B streptococcal infection (EOGBS) and determined those features associated with fatal infection. The incidence of EOGBS was 1.6 cases/1000 live births among 7960 inborn infants; the mortality rate for inborn and outborn infants was 28%. Multivariate analysis identified five features adequately predicting fatal outcome: birth weight <2500 g, absolute neutrophil count <1500 cells/mm3, hypotension, apnea and a pleural effusion on the initial chest radiographs. With these five variables and an initial blood pH <7.25, a clinical score was constructed that correctly predicted outcome in 93% of patients in this study (87% sensitivity, 95% specificity). Autopsy findings in 16 of 19 infants with fatal EOGBS suggested that surfactant deficiency respiratory distress syndrome was common in preterm infants with EOGBS and contributed to their higher mortality compared with term infants.