Purpose of the study Medical workers represent in France a majority of the population exposed to artificial ionizing radiation: medical applications of ionizing radiations employ more than 100,000 people, on a total of approximately 210,000 workers occupationally exposed. Results The most important doses, about a few mSv, are recorded in nuclear medicine departments. The personnel is confronted with an external exposure risk when using radioactive molecules and during the performance of conventional imaging examinations, and with a contamination risk by handling unsealed sources. Internal radiotherapy, which has been restricted to thyroid cancer for a long time, was recently extended to many of other types of cancers because of the availability of new vectors and new radionuclides. All these technological developments have an implication in radiation protection with regard to nuclear medicine personnel exposure. Discussion Radiation protection is based on census of risk situations, evaluation of expected doses, workplace studies, optimization of exposures and practices. They lead to the categorization of personnel and involve radiological zoning according to the radiological risk, and improvement of practices. Occupational exposure surveillance is made by external dosimetry, radiochemical analysis and individual medical survey, adapted to each working station. Generalization of ring dosimeters is essential to better monitor to the finger doses. Conclusion The level of personnel exposure remains nevertheless much lower than the regulatory limits. The only biological effects of ionising radiations to be feared are stochastic by nature: radiation-induced solid cancers or leukemias.