Background: Previous studies have suggested an increased risk for Helicobacter pylori infection in physicians who perform UGI endoscopy because of exposure to potentially infectious gastric secretions. Therefore, the H. pylori infection status of the endoscopy staff was compared with the H. pylori prevalence of medical staff without endoscopy experience and control subjects who had no contact with patients. Methods: The noninvasive ¹³C-urea breath test was performed in 2108 volunteers: 1460 physicians (mean age 44 ± 12 years), 235 nurses (33 ± 10 years), and 413 control subjects (43 ± 12 years) who were not working in clinical medicine. All subjects completed a questionnaire concerning the weekly frequency of gastroscopies and the duration of endoscopic experience. Results: Overall, 37.4% of the physicians and 35.3% of the nurses, but only 27.1% of the control subjects were infected. H. pylori infection was not significantly different between endoscopy-performing (37.8%; n = 1091) and general medical staff (35.9%; n = 604). Neither the frequency of gastroscopies nor the duration of endoscopy practice correlated with H. pylori status. With respect to the age distribution; however, a statistically significant higher prevalence of H. pylori was observed in physicians and nurses compared with the 413 control subjects without patient contact (p < 0.01). Conclusion: UGI endoscopy is not a risk factor for H. pylori infection, but medical practice slightly raises H. pylori acquisition. (Gastrointest Endosc 1997;46:305-10).