Helicobacter pylori is a widely occurring bacterium with a predilection for the gastric mucosa, and it can cause severe disease - gastritis, peptic ulcer and gastric carcinoma. Oral-to-oral transmission is generally believed to be the main route of infection. As endoscopes are contaminated after a gastroscopy, gastroenterologists and the nurses who assist them may be at elevated risk of infection. The epidemiological studies on this issue have been evaluated and summarised. Seven methodologically sound studies have been published, and five of these found a statistically significantly elevated risk of infection for gastroenterologists. Helicobacter pylori -related disease in gastroenterologists accordingly fulfils the criteria for acceptance as an occupational disease, even without the demonstration of a specific source of infection. The study results for nurses assisting with gastroscopy are more equivocal. Of the five methodologically sound studies, two found a statistically significantly elevated risk of infection. If there is any elevation of the risk of infection for nurses assisting at gastroscopies, the studies suggest that this is less pronounced than for gastroenterologists.