Back ground: S. agalactiae which are group B Streptococci asymptomatically colonize thernvaginal or rectal areas of 10 to 30 % of pregnant women. In these women, S. agalactiae mayrncause preterm labor or membrane rupture, as well as urinary tract infections,rnchorioamnionitis, postpartum endometritis, postpartum wound infection, septic pelvicrnthrombophlebitis, endocarditis and sepsis. These bacteria is a major cause of invasiverndisease at all ages and is the most frequent cause of serious bacterial sepsis, includingrnneonatal meningitis. rnObjective: This study was undertaken to determine the carriage rate of S. agalactiae and tornassess their antimicrobial susceptibility pattern. An attempt has been also made to identifyrnthe possible risk factors related with S. agalactiae colonization. rnMethods: Rectal and vaginal swabs were obtained from 150 pregnant women at 35-37rnweeks of gestational period that attended anti natal clinic at Adigrat Zonal Hospital andrnAdigrat Health Center. The specimen was cultured on selective CHROMagarrn StrepB andrnincubated aerobically at 37rnornc for 18-24 hours. Suspected colony of S. agalactiae mauverncolony (pink color) was confirmed by gram stain, catalase test, Christie, Atkins, MunchPetersonrnrn(CAMP) testing and latex agglutination (serological) test. In cases of positiverncultures obtained, antibiotic susceptibility tests were carried out on all S. agalactiae isolatesrnusing the disc diffusion technique on Mueller-Hinton agar supplemented with 5% sheeprnblood and incubated at 37rn0rnc for 20-24 hours in 5% corn. A univariate and multivariate binaryrnlogistic regression model was used to ascertain the association between the frequencies ofrncolonization in relation to the different variables. rn2rnResults: Seventeen of the study participants (11.3%) were colonized by S. agalactiae.rnThirteen (76.5%) of the isolates were from health center and 4(23.5%) werfrom hospital.rnThe study revealed a higher colonization rate among the age group 21 to 30 years (76.5%)rnbut one pregnant woman with S. agalactiae was identified (5.9%) in women aged lesser rnthan or equal to 20 years. Bacterial resistance was not detected against ampicillin, penicillinrnG, amoxacilline and vancomycin, whereas 11.8% and 17.6% of the isolates were resistant to rnTMerythromycin and clindamycin respectively. Intermediate susceptibility was also detected inrn2 isolates (11.8%) against erythromycin and in 2 isolates (11.8%) against clindamycin. Byrnmulti variant logistic regression analysis, Prolonged rupture of membrane was associatedrnwith a higher colonization rate of S. agalactiae (OR=5.864, 95% CI= 1.395 â€“ 24.643, Pvalue=rnrn0.016). No significant association was identified between S. agalactiae colonizationrnrates with other socio- demographic/gynecological characteristic of the pregnant women. rnConclusion: The carriage rate of S. agalactiae in the study area was 11.3%. High S.rnagalactiae isolates were detected from Adigrat Health Center. Prolonged rupture ofrnmembrane was strongly associated with the colonization of S. agalactiae. Based on thernfinding, penicillin G was the best antibiotic for the treatment of S. agalactiae. Out of thernisolates 11.8% were resistance to erythromycin and 17.6% were resistance to clindamycinrnCommon resistance to erythromycin and clindamycin was seen in two isolates.