BACKGROUND. The epidemiology of Helicobacter pylori infection reflects the age-characteristics, developmental status and access to health care of the population in a given area. AIM: To assess the influence of demographic variables on the prevalence of H. pylori status among patients evaluated in a Swiss university medical center. METHODS. Demographic data (i.e. age, gender, place of birth), indication for H. pylori testing, history of prior H. pylori eradication therapy, medical field and clinical setting of the referring physician were reviewed from patient's charts. H. pylori status was assessed by the 13C Urea breath test. RESULTS. Patients born in Switzerland had lower rates of positive 13C Urea breath test results compared to those born outside of the country (12/101 [11.9%] vs. 67/252 [26.6%]; p=0.003). While there were no differences between males and females (p>0.05), patients 50 years and below were more likely to have a positive test result compared to those above the age of 50 years (59/106 [28.6%] vs. 20/147 [13.6%]; p<0.01). There were no major differences in the rate of positive 13C Urea breath tests in patients with previous history of H. pylori eradication and those without. Patients with dyspeptic symptoms and those without had similar rates of positive tests (11/61 [18.0%] vs. 68/292 [23.3%]; p=ns). CONCLUSION. Epidemiologic characteristics of H. pylori infection in Western countries are influenced by changing demographics. Further studies are warranted to investigate reasons for the changing trends in the prevalence of H. pylori infection.