This paper aims to draw the attention of Bulgarian gynecologists, pediatricians, microbiologists on group B streptococci as a cause of serious invasive neonatal diseases associated with high mortality rate or disability. Epidemiology, pathogenesis and clinical features of the infection are described. Data on the antibiotic susceptibility and recommendations for treatment are presented. The main purpose of the paper is to lay particular stress on the importance of intrapartum antibiotic prophylaxis for pregnant women who are positive for rectovaginal group B streptococcal colonization. This measure was introduced in the USA (guidelines from 1996, 2002, 2010 years), it proved its efficacy and now a lot of the European countries put efforts to adopt it in their health-care system.