Objectives: We aimed to evaluate the vaginal colonization of pregnant women with beta hemolytic streptococcus as an important cause of early- onset and late- onset neonatal infections. Material and Method: From November 1999 to March 2000 total 150 vaginal swab samples were taken from 150 pregnant women admitted to the outpatient clinics of Obstetrics and Gynecology at Þiþli Etfal Hospital. Each of the samples was inoculated for evernight growth onto Todd-Hewitt infusion medium containing colistin sulfate 10 mg/lt and oxolynic acid 5 mg/lt and transferred onto Columbia agar containing 5% sheep blood and the same antibiotic proportions. After 24 hours of aerobic incubation at 37.C the recovered microorganisms which had narrow beta hemolysis were aplified onto 5% sheep blood agar. The typing of the bacteria was made using catalase test, CAMP test and the resistance patterns to bacitracin and trimethoprim/sulfametoxasole antibiotics. The definitive typing of Streptococcus agalactiae was made by using streptococcus latex agglutination test and BBL Crystal Gram Positive ÝD System/GP. Results: In this study 12 of the evaluated 150 pregnant women had vaginal colonization with group B streptococcus species which resembles 8%. Conclusion: As group B streptococcus is an important cause of fatal infections in the newborn the vaginal colonization of pregnant women should be determined before labour and the prevention of the neonatal infections can be done with intrapartum intravenous administration of antibiotics.