Abstract: The Chernobyl nuclear station accident is the unprecedented catastrophic accident in human nuclear industry with a large of quantity of radioactive nucleons resulting in contamination in many countries of the Northern Hemisphere. After almost 20 years studying, it is approved that Belarus is the most serious affected country by the accident. Eespecially thyroid carcinomas in the people exposed to radioactive fall, out is considered to be the only one late radiation effect. RET gene in the happening of thyroid carcinomas is being paid close attention at present.