Objective: The aim of the study was a retrospective analysis of the frequency of group B streptococci (Streptococcus agalactaie; GBS) carriage in pregnant women from the region of Krakow, together with an analysis of their drug resistance, carried out between 2008–2012. Materials and Methods: The study included 3363 patients of the Rafal Czerwiakowski Na Siemiradzkiego Hospital in Krakow. It was conducted in accordance with the recommendations of the Polish Gynecological Society for the detection of GBS colonization in pregnancy and prevention of infections in newborns. To assess colonization rates, vaginal and rectal swabs from pregnant women between 35 and 37 weeks of gestation were cultured. Swabs were cultivated in selective broth medium and subsequently plated on blood agar plates. Species identification was done with serological, biochemical and CAMP testing. Drug resistance was performed by the Kirby-Bauer method using penicillin, ampicillin, clindamycin, erythromycin, nitrofurantoin and ofloxacin discs. The results were interpreted in accordance with the guidelines of EUCAST 2012. Results: A high percentage of pregnant women who are carriers of group B streptococci was demonstrated. Each year covered by the study, it was in the range of 25%-30%, with an average value equal to 28%. The results confirm the need for taking swabs from both the vagina and anus since 15% of GBS-positive patients showed only rectal carriage. Should such material be omitted in the diagnosis of carriers, false negative results could be obtained. High proportion of isolates resistant to erythromycin was detected, which during the study period ranged from 22% to 29%, with an average value equal to 25%, as well as a high proportion of isolates resistant to clindamycin being 17%-25%, with an average of 20%. Conclusions: The results indicate the need to standardize the methodology of collecting samples for GBS testing and introduce microbiological diagnostic standards in all gynecological and obstetric centers in Poland in order to carry out a detailed epidemiological analysis in our country.