Background.The main approach to Hodgkin’s lymphoma (HL) treatment is the use of cytostatic and consolidation radiation therapy. The combination of both treatment techniques undoubtedly improves the antitumor effect, but also negatively influence on the functioning of the endocrine glands. The most frequent complications are various diseases of the thyroid gland.Objective.Our aim was to determine the relationship between the thyroid disorders and critical dose of neck irradiation in patients with Hodgkin’s lymphoma.Methods.The study included 143 patients aged 2–17 years with HL. In the treatment of all patients, risk-adapted therapy was used: 42 patients were treated according to the DAL-HD protocol, 86 patients — according to the original risk-adjusted SPbHL protocol, and 15 patients included in the unfavorable prognosis group underwent 6 courses of BEACOPP-basic. The next treatment step was consolidation radiation therapy. When the therapy course was completed, patients were diagnosed with structural and/or functional changes in the thyroid gland.Results.The majority of the patients (n =126) received concomitant cervico-supraclavicular radiotherapy involving mediastinal lymph nodes in the total focal dose (SOD) of 15–46 Gy. The mean follow-up period was 7.5 years (range: 0–22). Having performed ROC analysis, we determined the critical dose of radiation leading to the development of thyroid dysfunction — more than 39 Gy; the area under the curve was 0.717±0.108 (CI 0.590–0.822; p =0.0445). The Youden’s Index was 0.3929.Conclusion.Irradiation of the neck and thyroid in total dose of 39 Gy and above is associated with a high risk of developing thyroid dysfunction.