BACKGROUND/AIMS: Health care workers inevitably encounter many physical hazards including ionizing radiation, and have increased levels of psychological disturbance. This study was designed to investigate the prevalence of functional gastrointestinal disorders among hospital radiation workers and to determine significant factors associated with these results. METHODS: Whole body radiation doses of radiation workers were evaluated using the electronic dosimeter. The prevalence of functional dyspepsia (FD) and irritable bowel syndrome (IBS) were assessed by the bowel symptom questionnaire. The subjects were classified according to radiation dose, sleep quality, and psychological stress level, and the prevalence of FD and IBS was comparatively analyzed. RESULTS: A total of 70 subjects were recruited. The prevalence of FD and IBS was 31.4% and 22.9%, respectively. The average radiation dose per exposed worker for 1 year was 0.56+/-0.92 mSv. By multivariate logistic regression analysis, a significant factor associated with the prevalence of FD was their high level of stress (odds ratio, 6.37; 95% confidence interval, 1.38-29.53). Between radiation workers with IBS and those without IBS, there was no significant difference in radiation exposure level, sleep quality, and stress level. There was no difference in the prevalence of IBS (40.0% vs. 15.8%, P=0.09) and FD (30.0% vs. 31.6%, P=0.92) between the relatively high-dose (total dose accumulated during the 3 years > or =9.4 mSv) and low-dose exposed group (<9.4 mSv). CONCLUSIONS: Occupational exposure to low levels of radiation does not seem to be significantly related to IBS and FD, but high stress level seems to be related to FD.