The incidence of early-onset group B streptococcal (GBS) sepsis in the neonatal population has decreased substantially since the introduction of maternal intrapartum antibiotic prophylaxis and routine prenatal screening. However, these strategies have not reduced the incidence of late-onset GBS infections. Additional research pertaining to the transmission of late-onset GBS infections is required to develop effective preventive methods. The present report describes probable horizontal transmission of late-onset GBS infection among three infants in a neonatal intensive care unit. GBS strain confirmation was based on the microbiological picture, antibiogram and pulsed-field gel electrophoresis. These cases highlight the morbidity associated with late-onset GBS disease and the importance of considering horizontal transmission as an etiological factor in GBS infection in the newborn period. Further studies assessing horizontal transmission in late-onset GBS disease may improve prevention and early intervention.