Introduction. Fine needle aspiration biopsy is a non-surgical invasive diagnostic method for the cytological evaluation of the thyroid gland. Complications of fine needle aspiration biopsy are rare. Case Report. A female patient, 64 years of age, underwent left-sided nodulectomy in 2006, due to a follicular adenoma of the thyroid gland. In September of 2016, ultrasonography of the thyroid gland confirmed a node in the right lobe, approximately 10 mm in the longest diameter. The thyroid-stimulating hormone level was within the reference range (1,8 mIU/L), as well as calcitonin and carcinoembryonic antigen levels, but with elevated anti-thyroid peroxidase antibodies and anti-thyroglobulin antibodies, so fine needle aspiration was indicated. The cytological finding indicated a suspected follicular lesion and total thyroidectomy with an ex tempore biopsy was proposed in November of 2016. Prior to the surgery, hormone levels were measured and high thyroid-stimulating hormone levels were recorded (79 mIU/L). Further investigation showed low levels of free thyroid hormone concentrations, and levothyroxine was initiated at a dose of 75 mcg per day and the surgical treatment was delayed. The indicated dose of levothyroxine resulted in satisfactory values of the thyroid gland free hormones, and in February 2017, right-sided lobectomy was performed, whereas the histopathological findings indicated lymphocytic thyroiditis. Levothyroxine replacement therapy showed satisfactory results in the postoperative period. Further outpatient ultrasonographic monitoring showed a residual thyroid tissue, with slightly non-homogeneous echostructure in the left thyroid bed, 12 x 11 x 32 mm in size. Regular follow-up was suggested. Conclusion. Hypothyroidism has not been reported as a fine needle aspiration complication in the available literature.