The surgical treatment of goiter with severe thyrotoxicosis may lead to an improvement of the general condition of the patient, and amelioration of the clinical manifestations of thyrotoxic cardiomyopathy. The aim of the study was to evaluate the long-term results of surgical treatment in patients with toxic goiter and severe thyrotoxicosis, including the study of changes in cardiac activity and the level of physical activity. Materials and methods. The study was conducted in 123 patients with toxic goiter and severe thyrotoxicosis treated surgically. The duration of thyrotoxicosis ranged from 18 to 74 months. Before the surgical treatment and one year after it, structural and functional changes of the heart were studied by echocardiography and electrocardiogram, and physical activity according to the six-minute walk test. The long-term effects of treatment were considered good, satisfactory, unsatisfactory and ineffective. Results. The results of surgical treatment depend on the severity of the manifestations of thyrotoxic cardiomyopathy. Good and satisfactory results were obtained in 44.7% cases, unsatisfactory results in 32.5% and ineffective treatment was found in 22.8% cases. Conclusions. The surgical treatment of patients with toxic goiter and severe thyrotoxicosis allows eliminating thyrotoxicosis and in some patients the rhythm disorders, reducing the intensity of clinical manifestations of thyrotoxic cardiomyopathy and improving the capacity of physical activity.