Blood level of nine hormones and one enzyme were measured in twelve patients with the aortitis syndrome and in seven normal women in order to analyze the endocrinological environment of the aortitis syndrome. The hormones and enzyme measured were: pituitary system: TSH, ACTH; adrenal cortex: dehydroepiandrosterone-sulfate (DHEA-S); adrenal medulla: adoenaline (AD); sympathetic system: noradrenaline (NA); renin-angiotensin-aldosterone system (RAA): plasma renin activity (PRA), angiotensin- I (AT I), angiotensin- II (AT II), angiotensin converting enzyme (ACE), aldosterone (ald). The insulin-induced hypoglycemic stress test was introduced to further evaluate TSH, ACTH, DHEA-S, AD and NA. The hypoglycemic stress test revealed decreased reaction of the pituitary gland, adrenal cortex, adrenal medulla and sympathetic system in the patients with the aortitis syndrome. The RAA system showed unique results. The first half of the system was remarkably exaggerated, although the second half remained inappropriately in the normal range. These results suggest that the patients with the aortitis syndrome were in a state of hyperreninemic hypoaldosteronism with a shift of hormonal metabolism in the adrenal cortex. Discriminant analysis proved the most important hormones unique to the aortitis syndrome to be AD, DHEA-S and PRA. We concluded that the endocrinological changes seen in patients with the aortitis syndrome were a remarkable increase in PRA superimposed by hyperreninemic hypoaldosteronism, impaired function of the adrenal cortex associated with metabolic shift and markedly diminished function of the adrenal medulla.