From July, 1974 to February, 1978, we managed 12 infants with listeriosis. This infection presented in two distinct forms: an early-onset type (nine patients), often representing a congenital infection following maternal illness, and a late-onset type in which the patient presented with meningitis (three patients). Of our nine infants with early-onset disease, three died, three developed permanent sequelae, and only three were normal at follow-up. Appropriate early management in the perinatal period may improve the outlook in this condition. Affected infants were often premature and had pneumonia, rash, and hepatosplenomegaly at birth. Prenatal clues to the diagnosis included maternal fever, abdominal pains, and leukocytosis with meconium staining of the preterm amniotic fluid. Examination of gastric aspirate at birth showed gram-positive coccobacilli. Antibiotic therapy should be started prenatally and continue for three weeks after birth to prevent recurrences of the late-onset type. This late-onset disease presented as meningitis after the second week of life and responded well to antibiotics. Our three patients recovered without sequelae.