During a five-day period, four neonates in a neonatal nursery developed Campylobacter entercolitis. Investigations suggested that cross-infection or common-source infection were unlikely and that the neonates acquired their infection during delivery from their respective mothers, three of whom were also found to harbour Campylobacter jejuni in their stools. This suggestion was confirmed with use of the Lior serotyping system in a blind fashion. Each neonate was infected with a different serotype, and each of the three culture-positive mothers had the same serotype as her neonate. Examination of multiple colonies from the stools of five individuals showed that each was likely to have been infected by only one serotype. The presenting clinical features in the four neonates provides further evidence that neonatal Campylobacter entercolitis typically manifests as a benign, self-limited, nonfebrile, diarrheal illness with bloody stools.