Increased peripheral metabolism of cortisol may explain compensatory ACTH-dependent adrenal steroidogenesis and hence hyperandrogenism in polycystic ovary syndrome (PCOS). Previous studies have described an increased 5alpha-reduction of cortisol or impaired regeneration of cortisol by 11beta-HSD1 in PCOS. However, these observations may be confounded by obesity. Moreover, the relationship between alterations in cortisol metabolism and the extent of adrenal androgen hyper-secretion in response to ACTH has not been established. This study aimed to examine the association between cortisol metabolism and ACTH-dependent adrenal hyperandrogenism in PCOS, independently of obesity.