Fifty-four hyperandrogenized women were studied to evaluate the importance of the adrenal or ovarian contribution to androgen secretion. Forty-six had the polycystic ovarian (PCOD) syndrome. Eight normal women represented a control group. The endocrine study was performed during the follicular phase. The plasma samples were collected at 7.00 am (A1) and at 11.00 pm (A3). Dexamethasone 2 mg was administered orally at 11.30 pm and blood samples were collected the day after, at 7.00 am (B). The adrenocorticotropic hormone (ACTH) was injected, 250 micrograms i.v. and samples were collected after 60 min. Cortisol dehydroepiandrosterone-sulfate (DHEAS), androstenedione, testosterone and 17-hydroxyprogesterone (17OHP) were measured. The hyperandrogenized patients had A1 androgen levels higher than the controls (p less than 0.01). 17OHP and androstenedione A3 values showed a cortisol-related decrease. After dexamethasone, androgen levels, since DHEAS, were normalized in all patients. We found that baseline androgen levels and circadian and dexamethasone-inhibited amounts were strongly correlated (p less than 0.01). The ACTH test revealed five cases of enzymatic adrenal deficiencies. Moreover, the amplitude of the response of 17OHP and androstenedione to ACTH is predictable in relation to both circadian and dexamethasone-inhibited amounts (p less than 0.01). In conclusion, our study confirms and makes quantifiable the importance of the adrenal contribution to androgen secretion in hyperandrogenized patients. The ACTH test is important for detecting the presence of mild enzymatic adrenal defects.