We investigated parameters of thyroid and endocrine functions in 100 HIV-infected men who were grouped according to the CDC criteria. Progression of the disease was associated with a 44% increase in plasma TBG and a 15% increase in plasma CBG, while the T4/TBG ratio was decreased by 20%, plasma DHEAS was lowered by 30% and urinary aldosterone excretion fell by 70%. Plasma T4, T3 and TSH and urinary excretion of cortisol and catecholamines was not influenced by the disease. A weak, but significant negative correlation was found between plasma CBG and the body mass index of the patients. Significant positive correlations were observed between CD-4 cell count and the T4/TBG-ratio or plasma DHEAS levels. TBG was inversely correlated with CD-4 cell count and DHEAS. Thus, an increase in plasma TBG and a shift from adrenal androgen and mineralocorticoid steroid secretion towards cortisol secretion may be endocrine markers for progression of the disease in patients with HIV-infection.