Changes in the cell immunity indexes under the influence of thymalin, thyroxin and fibronectin in vitral loading models were studied up in patients with hyperplastic diseases of the thyroid gland. Disbalance of the cell link immunity was revealed before the operation and, in particular, in the main subpopulations of lymphocytes as well as immunoregulating index lowering, which had intensified after the operation. In patients with toxic, nodose euthyroid goiter and chronic autoimmune thyroiditis the existence of (thyroxin- and thymalin) dependent control of the cell link immunity was determined. Application of fibronectin substituting therapy for correction of the hormone depending functional activity of lymphocytes in the early postoperative period in patients with hyperplastic diseases of thyroid gland was pathogenetically substantiated.