Streptococci of Lancefield Group B (GBS) are known to cause maternal sepsis and neonatal infection, whereas streptococci Lancefield Group A (GAS) cause vulvo-vaginitis in both children and adults. Prevalence of SGB colonization of the lower genital tract of normal women is between 4-18%, with higher rates found in hospital personnel and delivery rooms. Such high carriage rates may be a significant factor in nosocomial transmission of GBS to neonates. Symptomatic infection is uncommon and usually secondary to other pathological states. Amnionitis is a complication of vaginal carriage of GBS and there is now evidence that chorioamnionitis is associated with pre-term labour and its attendant problems. GBS infection of the male genitalia has also been described. Intrapartum chemoprophylaxis has been shown to prevent early onset GBS disease of the neonate. Prevalence of GAS in the genital tract is lower than that for GBS, but is more likely to be symptomatic. The response to penicillin is usually prompt. Optimal drug regimens need to be determined, particularly for use in pregnancy.