Aim — to study the possibility of determining the indications for choice of the extent of surgery in patients with unilateral nodular goiteragainst the background of autoimmune thyroiditis(AIT) with compression syndrome and prognosis for the long-term results of surgical treatment.Materials and methods. The analysis has been performed for the long-term results of hemithyroidectomy in 101 women aged from 23 to 72, patients with unilateral nodular goiteragainst the AITbackground with compression syndrome. It has been established what exactly indications to the surgery,includingvolume of the gland, echostructure variant, blood levels of thyroid stimulating hormone(TSH), free thyroxine and triiodothyronine, thyroid peroxidase(TPO) antibodies, apoptosis and proliferation indicators, provided satisfactory and unsatisfactory treatment results.Results. Based on the results of investigation in 3 years after hemithyroidectomy, no violations of the functional state of the thyroid glandwere revealed in 75 patients; in them ultrasoundinvestigation of parenchyma of the remaining lobe of the gland showed that pre-operativeAITsigns did not progress or progressed without hypothyroidism and changes of the variant of ultrasound picture (satisfactory result). In 26 patients an increase in the volume of the remaining part of the thyroid gland and progression of the autoimmune process with the development of hypothyroidism were established (unsatisfactory result).One can expect the satisfactory result of hemithyroidectomy in the treatment of patients with unilateral nodular goiteragainst the AIT backgroundwith compression syndrome in cases where at the time of surgery the volume of the lobe does not exceed 10 cm3, its echostructure corresponds to hypoechoic and heterogeneous and pseudomicronodular variants, TSH is not higher than 2.85 IU/L, levels of free thyroxine and triiodothyronine are not lower than 16.7 and 5.3 pmol/l, respectively, TPO antibodies level is not higher than 150 IU/ml.Conclusions. One of the possible options for surgical treatment of patients with unilateral nodular goiteragainst the AIT background with compression syndrome may be hemithyroidectomy with preserved hormonal function of the gland and structural changes in the parenchyma in the lobe, which remains at the level of hypoechoic and heterogeneous or pseudomicrous variants. Hemithyroidectomy is contraindicated in cases of pseudolarge nodular and severe variants of parenchyma echostructure of the thyroid gland.