Background:The prevalence of gestational diabetes mellitus (GDM), as a complex problem in pregnancy, is increasing all over the world, but most noticeable in developing countries.Aims:To estimate GDM prevalence and associated pregnancy features in the southern part of Bosnia and Herzegovina.Methods:A cross-sectional observational study was conducted from October 2010 through March 2011. A total of 285 pregnant women with singleton pregnancies participated and were asigned to the study in the order they came for their usual ante-natal clinic examination. They underwent an oral glucose tolerance test (OGTT) with 75 g of glucose. Information on OGTT results, maternal characteristics and pregnancy outcomes were collected from database and medical records.Results:Prevalence of GDM was 10.9% according to 1999 World Health Organisation (WHO) diagnostic criteria. Prenatal cigarette smoking, previous GDM, cesarean delivery rate and neonatal hypoglycemia were significantly more frequent in the GDM group compared to the group of pregnancies with normal glucose tolerance (p = 0.015, p < 0.001, p = 0.015, p = 0.002).Conclusion:This study presents a relatively high prevalence of GDM in Bosnia and Herzegovina. There is a need for large well-designed study on GDM prevalence and its other features.