SummaryObjective Polycystic ovary syndrome (PCOS) is a complex endocrine disorder associated with insulin resistance, hyperandrogenism, obesity, altered gonadotrophin release and anovulatory infertility. Anti-Mullerian hormone (AMH) has been proposed as a marker of ovarian function and fertility. Across a cohort of lean and overweight women with and without PCOS, we investigated the association of AMH with insulin resistance and body composition using gold standard measures. A secondary aim was to examine whether AMH was useful to determine PCOS status. Design Cross-sectional study. Patients A total of 22 lean and 21 overweight women with PCOS and 19 lean and 16 overweight non-PCOS healthy controls were recruited. PCOS was diagnosed based on the Rotterdam criteria. Measurements Euglycaemic-hyperinsulinaemic clamp for assessing insulin resistance, dual energy X-ray absorptiometry and computed tomography for assessing adiposity, and blood sampling for the assessment of androgens, gonadotrophins and AMH. Results Anti-Mullerian hormone levels were increased in women with PCOS (P
