The usefulness of the guideline recommended in 1976 by the World Health Organization (WHO) for the differential diagnosis of ovarian sterility needs critical reevaluation, since it does not take into account new aspects such as the pulsatility of GnRH secretion, androgen excess, or thyroid disorders and other phenomena related to ovarian dysfunction. In order to demonstrate the relative frequency of such phenomena, the authors examined 183 women with secondary amenorrhea of more than three months' duration (mean +/- SD = 12.7 +/- 18.4 months). The endocrine status of these women was examined under standardized conditions in two clinical endocrinology units in the cities of Hamburg and Berlin. The percentages of abnormal hormonal data (greater than mean +/- SD + gray zone) were as follows: testosterone (T) 39.9%; DHEA sulfate (DS) 29.5%; prolactin (PRL) 18.0%; TSH 11.5%; FSH or LH 26.8%; estradiol (E2) 30.1%. Among 96 patients with increased T and/or DS (52.5% of all patients), 53 patients (55.2%) did not show any clinical signs of androgenization (hirsutism, acne). Retrospective evaluation of all data revealed that a stepwise diagnostic procedure would have resulted in the following cumulative percentages of hormonal abnormalities: (1) T = 39.9%; (2) +DS = 52.5%; (3) +PRL = 60.2%; (4) +LH/FSH = 82.0%; (5) +E2 = 91.2%; (6) +TSH = 92.3%. Only in 7.7% of all patients were all hormonal parameters within normal ranges. Individual case analysis showed that 52.5% of all patients had hyperandrogenemia, while 18% had hypothalamic amenorrhea without any other pathologic condition; 17.5% had hyperprolactinemia and 3.3% primary ovarian insufficiency. Another 4.9% had hypothyroidism only, while 1.1% had exclusively hyperthyroidism. Combined hormonal deviations were found in 24% of all patients. Considering the differential diagnosis of secondary amenorrhea from an economic point of view, one comes to the conclusion that direct and indirect expenditures are similar in magnitude, no matter whether one prefers a conventional stepwise procedure or a one-step hormonal analysis encompassing all potentially relevant hormones (DM 859.00 + 10 weeks waiting time vs. DM 827.50 + 1 week waiting time). Androgen excess is much more frequent than was believed; hirsutism and/or acne by no means necessarily occur in cases of androgen excess. Hyperprolactinemia is less frequent than hyperandrogenemia. Thyroid status should be evaluated in all women with functional amenorrhea. The stepwise diagnostic procedure as recommended by the WHO is time-consuming, complicated, and sometimes incomplete in the diagnostic work-up, with obvious potential disadvantages for therapy.(ABSTRACT TRUNCATED AT 400 WORDS)