Introduction: Group B Streptococcous (GBS) is a causing agent for neonatal infections such as meningitis and septicemia, and plays a significant role in maternal infections including pyelonephritis, chorioamnionitis and postpartum infections. The aim of this study was to determine the prevalence of GBS colonization in pregnant women in Jahrom in 2014.Materials & Methods: A total of 403 pregnant women in their 35–37th gestational week, presenting to Honari Clinic in Jahrom participated in this study. Rectal and vaginal samples were taken, placed in transport media, and transported to the laboratory and tested for GBS. The results were analyzed in SPSS software.Results: In this study, the prevalence of positive vaginal, rectal and rectovaginal GBS cultures in pregnant women were 16.4%, 5.2%, and 1.7%, respectively. There was a significant correlation between the positive cultures and maternal age, history of genital diseases, and gestational hypertension, but not between positive cultures and abortion status, diabetes mellitus, preterm delivery, urinary infection, place of residence, nationality, education level, neonatal diseases after birth and cesarean section.Conclusion: Given the high prevalence of GBS colonization (19.9%) in pregnant women in Jahrom, it is suggested that obstetricians and gynecologists take appropriate measures to prevent this infection in pregnant women and infants.