Group B streptococcus (GBS) is the leading cause of neonatal sepsis and meningitis. Despite optimal treatment of GBS-infected neonates it is associated with significant morbidity and mortality, and prevention strategies are required. As disease occurs rapidly, and is often evident at birth or within 12 hours of birth, antibiotics must be given prior to delivery, and when administered early enough, and at the correct doses, they will prevent the majority of early-onset GBS cases. Prevention is therefore in the hands of obstetricians and midwives. Women at higher risk of delivering infected infants can be identified through one of two strategies: the presence of one or more clinical risk factors, or the presence of GBS on lower vaginal/rectal swabs obtained late in pregnancy. Decisions on which strategy to use will depend on a number of factors. A swab-based approach appears to have higher efficacy but is likely to lead to more antibiotic exposure.