Of 17 neonates with systemic, group B, β-hemolytic streptococcal infection, all but one died. Absence of prenatal or neonatal warnings of infection was striking, with only two patients having prolonged rupture of fetal membranes. Most were tiny, normally grown, premature infants and all had a low birth weight. Laboratory aids to early diagnosis (histological characteristics of the cord and IgM level) were notably absent, and the usual signs and symptoms suggesting neonatal infection were rare. Unexplained apneic episodes were common within three to four hours of birth in most infants. Coagulation disorders were detected before death in two infants and extensive hemorrhage was the most prominent autopsy finding. Neonatal infection with group B, β-hemolytic streptococcus appears to be a common lethal disorder that strikes with but little advance warning.