The administration of stable iodine in order to keep the thyroid gland away from radioactive iodine isotope contamination has long been regarded with caution by the health authorities, mainly because of the potential toxicity of iodine in newborns, young children and adults with thyroid pathology. Therefore, the risk of oral stable iodine given for a limited period of time must be compared to the risk of cancer due to radioactive exposure. The analysis of complications following the nuclear accidents of Marshall Islands in 1954 and Tchernobyl in 1986 has shown that newborn infants and young children, have the highest risk, the main complications being cancer (papillary carcinoma) and hypothyroidism. In the most exposed areas of Bielorussia, the incidence of child thyroid cancer has been approximately multiplied by 100. On the other hand, studies of children from Utah who were contaminated after nuclear tests in the Nevada desert have shown that following mild iodine radioactive exposure, the risk is not significant. Among complications attributed to stable iodine, only those related to an oral intake over a limited period of time should be considered. On the basis of nuclear medicine experience and scientific literature, the risk can be considered as negligible in adults but not in children. However, the Polish experience in children has reported a low risk and only benign complications, mainly transient hypothyroidism. Thus from current knowledge, it appears that the potent risks linked to stable iodine administration should not contraindicate the collective preventive stable iodine administration in case of nuclear accident.