A description was offered of radioimmunoassays (RIAs), the manufacturing of the RIA kit and components, and the regulations and precautions that guide RIA kit manufacture with specific attention given to the safe handling of the radioactive materials. Generally, in a radioimmunoassay, the technique separates labeled antigens of interest into bound and unbound fractions after incubation with an antibody in the presence of an unknown quantity of unlabeled antigen. RIA kits included the radiolabeled antigen, receptor, receptor/precipitating reagent, and the antigen standards and diluents. There have been two major types of radiation associated with radionuclides used to label antigens. The Nuclear Regulatory Commission has established the standard that the maximum permissible doses (MPD) for occupationally exposed workers is 1.25 rems per quarter for whole body, head and trunk, active blood forming organs, lens of eyes, or gonads; 18.75 rems per quarter for the hands and forearms, feet, and ankles; and 7.5 rems per quarter for the skin of the whole body. Matters of concern for designing the facility include control of access and egress, surface preparation for the occasional spills, and ventilation for the use of volatile radioiodine. Usually workers who are likely to receive more than 25 percent of the MPDs are required to wear personal dosimeters, including film badges, thermoluminescent dosimeter badges, pocket dosimeters, wrist film badges, and finger ring thermoluminescent dosimeters. Proper labeling for penetrating and nonpenetrating radiation was described.