Cardiac catheterization with angiography can deliver the greatest dose of x-radiation of any diagnostic medical examination. The physicians and technologists in the angiography room receive low-level scattered radiation over a period of months to decades. Although the radiobiology is complex, the physicians who perform cardiac catheterization should be familiar with the potential genetic and somatic effects of radiation and with the methods to reduce or eliminate x-ray exposure. The aim of radiation protection criteria is to reduce the risk of cancer death to less than the fatality risk for other occupations regarded as safe. This report is a review of the literature relating to radiation exposure and protection in cardiac catheterization laboratories. Catheterization personnel have control over the time duration of exposure, placement of technologists, shielding, location of equipment and monitoring of dose received.