Group B streptococci are a major cause of serious infections in the newborn, and also cause chorioamnionitis, late abortions, puerperal infections and sepsis. Group B streptococci are harboured in the genital tract of 5-40% of pregnant women, and 50-70% of their infants are colonized. Severe perinatal infections caused by group B streptococci affect 1-5 infants per 1,000 live births. American Academy of Pediatrics (AAP) have issued guidelines for preventing group B streptococcal infections. These are described, and it is suggested that these should be adopted in Norway.