Thyroid cancer is the most common malignant disease of the endocrine system. According to the latest estimates of the International Agency for Research on Cancer (IARC), in 2020, 586,202 people worldwide were diagnosed with thyroid cancer, and 43,646 people died. Women account for over 80% of all new cases in Europe, and 60% of deaths due to thyroid cancer. Thyroid cancer can occur at any age; in women it occurs more often in their forties and fifties, while in men it is more common in their sixties and seventies. According to the latest data from the Cancer Registry, in 2019, 831 people were diagnosed with thyroid cancer, of which 78% were women. Risk factors for thyroid cancer include exposure to ionizing radiation, a family history of thyroid cancer, low iodine in the diet, some rare hereditary syndromes, female sex, and low vitamin D levels. The Chernobyl disaster of 1986 and its consequences related to the incidence of thyroid cancer have been frequently investigated in the past decades. Despite the possible exposure to radionuclides after the Chernobyl nuclear disaster, the results of research conducted in Croatia did not show an undeniable link between the incidence of thyroid tumors and exposure to radionuclides after the Chernobyl disaster in individuals who were in the risk group (born between 1966 and 1986). Although trends in the world indicate a significant increase in the number of new cases of thyroid cancer, about 5% per year in the last 20 years, a large part of the increase in the number of new cases is attributed to better diagnostics and more frequent thyroid ultrasound examinations.