<b>Abstract</b> <p>This work is devoted to the study of the action of quercetin on radiosensitivity and induction of the radiation adaptive response according to the criterion of cytogenetic damage in bone marrow cells under irradiation of mice with low and medium doses of X-rays. It was found that a single intraperitoneal administration of quercetin at a dose of 27.9 mg/kg leads to a significant increase in the radioresistance of mice to X-rays radiation at a dose of 1.5 Gy 5 and 24 h after injection, but not 20 min and 1 h, and does not change the value of adaptive response. Administration of quercetin at a concentration of 279 mg/kg 1 h before irradiation increased the radiosensitivity of mice but resulted in the disappearance of adaptive response. The involvement of oxidative stress levels and heat shock proteins at different stages of induction and formation of adaptive response depending on quercetin concentration is discussed</p>