Streptococcus agalactiae (Group B streptococcus, GBS) is an important cause of neonatal morbidity and mortality. The aim of this study was to determine the serotype distribution and antibiotic susceptibility patterns of GBS isolated from pregnant women. A total of 671 pregnant women were screened for vaginal carriage of GBS, and vaginal colonization rate was found to be 14.6%. All GBS isolates were susceptible to penicillin, vancomycin, chloramphenicol and ofloxacin. The rates of GBS resistance to tetracycline, erythromycin and clindamycin were 81.6%, 24.5% and 19.4%, respectively. The serotype distribution of GBS isolates was as follows in order of frequency; serotype III (33.7%), serotype Ib (24.5%), serotype V (18.4%), serotype Ia (7.1%), serotype IV (3.1%) and serotype II (2%). Eleven GBS isolates could not be serotyped by the antisera set used in the study.