Although pregnant women must be screened for GBS as part of routine prenatal care, no problem estimation and no official Yemeni guidelines regarding GBS in pregnant women have been established. This cross-sectional study was conducted on 210 Yemeni pregnant women to investigate the prevalence rate of vaginal colonization by GBS for the first time in Yemen. The present study revealed that 10.95% of Yemeni pregnant women were vaginally colonized with GBS. This result is consistent with the findings of several similar studies from developing countries where the GBS vaginal colonization ranged from 10–15%. For instance, it was 11.8% in Iran [29], 10.4% in Ethiopia [30], 14% in Cameroon [31], and 15% in Bangladish [32]. However, GBS vaginal colonization in other countries was reported to be less than that of our. For example, it was 8.2% in China [33], 7.6% in Saudi Arabia [34]. and 2%in India [35]. Additionally, higher colonization rates were reported in other countries. It was 26% in Brazil [36], 19.5% in Jordan [15], and 30.9% in South Africa [37]. The variation of colonization rates among different studies is attributed to several factors, such as the site of swaping (vaginal, rectal or both), different numbers of participants, different personal hygiene behaviours, different sexual practices behaviours, antibiotic use, and different ways to isolate bacteria. In this study the prevalence was less than other studies owing to that we did not obtain approval from participants to take rectal swabs. Other possible factors are religion and culture belives, personal hygiene, sexual practices, and antibiotic use. By analyzing the relationship of different variables (parity, previous abortions, and educational level) with vaginal group B Streptococcus colonization, we did not find significant relationship between these variables and vaginal colonization (Table 1). This finding conforms to the findings of other research, such as [15, 29, 38, 39]. In the twentieth century the excessive use of antibiotics has heightened fear of raised concerns regarding the emergence of bacterial antibiotic resistance [40]. Therefore, earlier studies have also been performed to find out the sensitivity of group B Streptococcus and its resistance to various antibiotics [41–43]. According to the results of this study, the antibiotic sensitivity profile of GBS was as follows; all isolates were sensitive to penicillin, ampicillin, levofloxacin, cefotaxime, and vancomycin. These findings are close to those of other studies, such as [44] done in Nigeria, [45] in Saudi Arabia, and [30] in Ethiopia. Generally, Penicillin as yet the drug of choice for prophylaxis and treatment of GBS colonization in pregnant women. Thus, our results is consistent with different studies regarding the sensitivity to penicillin [30, 43, 45, 46]. Our study findings do not correspond to the Ethiopian research results where the highest resistance was observed against penicillin [47]. Women who were penicillin-allergic clindamycin is recommended for GBS prophylaxis during labor [42]. Group B Streptococcus resistance rate to different antibiotics have been detected to be increased in many regions of the world, including Europe [48], North America [49], and South America [50]. In the last 10 years, GBS strains had exhibited resistance to other antibiotics, including erythromycin and clindamycin [51]. Clindamycin and/or erythromycin resistance has already been notified earlier, ranging from 0.7–51.3% for erythromycin and from 1.7 to 50% for clindamycin. [52, 53]. Resistance rate of GBS to clindamycin in the current study was 8.6% and this rate is close to clindamycin resistant rate (5.1%) in Saudi Arabia [45]. The different antibiotic sensitivity rates of group B Streptococcus among different studies are due to many factors, such as antibiotics misuse, self-treatment with antibiotics, different isolated strains. The high sensitivity rates of GBS to members of beta-lactam family as well as its increased resistance to other antibiotics supports the pivotal role of penicillin and ampicillin as the first-line for intrapartum treatment to prevent neonatal early-onset infection by GBS.