Objective: to assess the incidence of newly diagnosed subclinical and manifest hypothyroidism in patients with ST-segment elevation myocardial infarction (STEMI) and to identify angiographic features of coronary artery lesions in this combined pathology.Materials and methods: in all patients with STEMI, the level of thyroid-stimulating hormone (TSH) was determined, and thyroid function was assessed if the TSH level deviated from the norm. Stage I of the study included 441 patients, stage II included 133 patients with STEMI. Depending on the presence of newly diagnosed hypothyroidism, patients were divided into 3 groups: 1st — patients without hypothyroidism (n = 57), 2A group — with subclinical hypothyroidism (n = 42) and 2B group — with manifest hypothyroidism (n = 34). All patients underwent coronary angiography and percutaneous coronary intervention.Results: newly diagnosed hypothyroidism occurred in 27.44% of patients with STEMI: subclinical — in 19.73%, manifest — in 7.7% of cases. Patients with concomitant overt hypothyroidism had significantly more severe atherosclerotic lesions of the coronary arteries compared to patients without hypothyroidism.Conclusion: a high incidence of newly diagnosed hypothyroidism in patients with STEMI was established (27.44% of cases). Multivessel coronary lesions were recorded more often in patients with overt hypothyroidism than in patients with subclinical hypothyroidism and without hypothyroidism.