Functional activity of the hypothalamo-hypophyseal-thyroid system was assessed by serum hormones. T3, T4, TSH and TTH were determined with radioimmunoassay. The study included 12 schizophrenics with sexual deviations, 19 schizophrenics without such and 25 mentally healthy subjects. It was found that schizophrenics with deviant behavior differ from those without deviations by subclinical hypothyroidism presenting with elevated levels of TTH in normal levels of T4 and low of T3. Proportions T4/T3 and T4/TSH rose in value. Hormonal and biochemical characteristics obtained confirm the role of endocrine disorders in promoting deviant behavior, thought these are not related to the deviation variety.