Medical radiation workers occupy the largest group of radiation workers and is rapidly increasing worldwide. They expose to protracted low-dose radiation and include a large proportion of women. The purpose of this article is to provide an overview of occupational radiation exposure and health effects among medical radiation workers through literature review and from the findings of Korean medical radiation workers’ studies. Occupational radiation exposure increases the risk of many chronic diseases including cancer, cataract, cardiovascular diseases, thyroid diseases, and others. Although Korean medical radiation workers had a more favorable mortality than in general population, male workers experienced higher mortality from all cancers, leukemia, cancers of the stomach and the colon, and diseases of circulatory system after adjusting for the lower overall mortality. The potential adverse health risks from occupational radiation exposure are not negligible in medical radiation workers if current working level remains. Therefore, effective prevention efforts are needed to reduce the risks of diseases from occupational radiation exposures. (Korean J Med 2018;93:237-246)