A 2-3 fold higher urinary pregnanediol glucuronide excretion has been observed in women with premature ovarian failure, compared with age-appropriate menopausal women. Progesterone, the precursor of urinary pregnanediol glucuronide, is a secretory product of either adrenal or ovarian origin. We postulated that suppression of pituitary gonadotrophin secretion by down-regulation with a long-acting gonadotrophin-releasing hormone agonist, leuprolide acetate, would decrease ovarian but not adrenal pregnanediol glucuronide. This would demonstrate a major difference in the ovarian hormonal milieu of these two groups of women. Four volunteers with premature ovarian failure collected daily first morning voided urine samples for 1 month prior to leuprolide acetate administration. Leuprolide acetate was then administered monthly for 3 months while continuing daily urinary collection. Luteinizing hormone (LH), follicle stimulating hormone (FSH), and pregnanediol glucuronide were measured in all samples and normalized for creatinine. Comparisons of pre- and post-median values for luteinizing hormone (LH), FSH, and pregnanediol glucuronide were made using the Wilcoxon rank sum test. This demonstrated significant suppression of both LH and FSH. Pregnanediol glucuronide, however, did not demonstrate a significant decline, strongly implying an adrenal source of the enhanced excretion. The decreased pregnanediol glucuronide noted in age-appropriate menopausal women compared with premature ovarian failure is likely to be a reflection of adrenal ageing.