The objective of the study was the comparison of AMH levels among obese or overweight and normal-weight women with the four different PCOS phenotypes and healthy controls. AMH levels were evaluated in four age- and BMI-matched groups of 25 normal-weight and 25 obese or overweight women each, belonging to the four main subsets of the syndrome, resulting from combinations of the three diagnostic criteria (Group 1: oligo-amenorrhoea (ANOV), hyperandrogenemia (HA) and polycystic ovaries on ultrasonographic evaluation (PCO), Group 2: ANOV and HA, Group 3: HA and PCO, Group 4: ANOV and PCO), and in 50 (25 obese or overweight and 25 normal-weight) age- and BMI-matched healthy controls. Age, BMI, W, FSH, LH, prolactin, testosterone, 4A, DHEA-S, 17-OH-progesterone, fasting insulin, glucose, AMH, FAI and HoMA-IR were analysed. AMH levels were significantly higher in PCOS groups 1 and 2, compared to groups 3 and 4 and the control group and higher in PCOS groups 3 and 4, compared to the control group. AMH levels were significantly increased in normal-weight, compared to obese and overweight women. AMH concentrations were independently predicted, in order of significance, by LH and testosterone levels, BMI (negatively) and the total number of follicles 2-9 mm in diameter. The differences in circulating AMH levels between the main phenotypic groups of PCOS women seem to reflect the severity of the syndrome, but are negatively affected by obesity. Increased LH levels might be the most significant independent link between PCOS-associated disorders of ovulation and the observed increase in circulating AMH concentration.