Objective: This study aims to determine the prevalence of genital tract group B streptococcus (GBS) colonization in a cohort of pregnant Irish women and to compare patient preference and efficacy of self-collected versus health professional-collected swabs.Study design: In this prospective cohort study, 600 pregnant women attending public and private antenatal clinics at the Unified Maternity Services, Cork were included. At 35-37 weeks of pregnancy, these women self-collected an ano-vaginal swab and a health professional-collected a second swab on same clinic visit. The women filled a questionnaire to indicate their preferences. Statistical analysis was performed on SPSS Version 13.Result: The cumulative prevalence of maternal GBS colonization was 11.7% (95% CI, 9.3-14.6). The sensitivity of the self-collected swab was 84.3% (95% CI, 73.2-91.5) and that of health professional-collected swab was 94.3% (95% CI, 85.3-98.2). While good agreement in efficacy was found between health professional and patient-collected swabs (Kappa = 0.87, p < 0.001, 97.5% measure of concordance), only 28.5% women preferred self-collection, while 43.2% preferred a health professional to collect the swab and 28.3% had no preference.Conclusion: In our study the concordance between health professional and self-collected swab was excellent. However, pregnant women mainly prefer a health professional to collect their ano-vaginal swabs. (C) 2007 Elsevier Ireland Ltd. All rights reserved.