Thirty-three infants with meningitis due to group B streptococcus were evaluated. There was a preponderance of females and white infants among the study group. Twenty of 23 serotyped cerebrospinal fluid isolates were type III. Twelve infants had early onset of meningitis (<10 days of age) characterized by an association with predisposing maternal obstetric complications, nonspecificity of symptoms and signs, severe illness, frequent isolation of group B streptococci from sites other than cerebrospinal fluid or blood, and a mortality rate of 58 per cent. Twenty-one infants had late onset of illness (>10 days of age) characterized by a history of few, if any, predisposing maternal obstetrical complications, typical symptoms and signs of meningitis, less severe illness, infrequent isolation of group B streptococci from sites other than cerebrospinal fluid or blood, and a mortality rate of 14 per cent. Uncomplicated recovery of the patient seemed to correlate with late onset of symptoms and the presence of mild disease on admission. Neurologic sequelae were detected in only one of 23 survivors. Thirty-three infants with meningitis due to group B streptococcus were evaluated. There was a preponderance of females and white infants among the study group. Twenty of 23 serotyped cerebrospinal fluid isolates were type III. Twelve infants had early onset of meningitis (<10 days of age) characterized by an association with predisposing maternal obstetric complications, nonspecificity of symptoms and signs, severe illness, frequent isolation of group B streptococci from sites other than cerebrospinal fluid or blood, and a mortality rate of 58 per cent. Twenty-one infants had late onset of illness (>10 days of age) characterized by a history of few, if any, predisposing maternal obstetrical complications, typical symptoms and signs of meningitis, less severe illness, infrequent isolation of group B streptococci from sites other than cerebrospinal fluid or blood, and a mortality rate of 14 per cent. Uncomplicated recovery of the patient seemed to correlate with late onset of symptoms and the presence of mild disease on admission. Neurologic sequelae were detected in only one of 23 survivors.