Group B streptococci (Streptococcus agalactiae) cause a number of infections in women during pregnancy and postpartum, such as urinary tract infection, chorioamnionitis and endometritis, consequently may affect the newborn. Group B streptococci is the most common cause of severe infections in newborns in developed countries. Studies on the epidemiology of group B streptococci infections in Latin America are still limited. This information is also unknown in Mexico, but studies carried out in the center of the country have found high rates of vaginal colonization in pregnant women and there are case series and case reports of newborns. Microbiological and molecular epidemiology studies in Mexico have shown that populations of group B streptococci have a clonal distribution and that there are clones with genetic and phenotypic characteristics of high virulence that appear to be responsible for most of perinatal pathology. However, the actual role of group B streptococci in perinatal pathology in Mexico is unknown. Consequently, whether to perform or not the screening for determining the group B streptococci colonization status in pregnant women, and the indication or not for intrapartum antibiotic prophylaxis to prevent neonatal group B streptococci infection in Mexico, are still controversial.