Group B Streptococcus (GBS)is a leading cause of invasive neonatal infections and a significant pathogen in immunocompromised adults. Screening to detect GBS colonization in pregnant women determines the need for antibiotic prophylaxis in that pregnancy. Universal screening for GBS and intrapartum antibiotic prophylaxis remains the main preventive strategy to reduce the neonatal mortality and morbidity secondary to GBS. Efficient determination of the GBS colonization status of pregnant women is crucial. This article presents the risk of GBS colonization and the various diagnostic methods for GBS species determination and the treatment.