Group B beta-haemolytic streptococci (GBS) are the most common cause of serious bacterial infection in the neonate. Neonatal GBS sepsis is divided into early onset (1st- 6th day) and late onset (LO) (after 6th day of life). The incidence of both is increased in premature infants and infants with a low birth weight. The pathogenesis of LO GBS sepsis is poorly elucidated. Breast milk has been suggested as a source of infection. We describe three cases of sepsis in a premature girl nourished with mother's milk which illustrate the importance of investigating breast milk as a source of infection.