Purpose To assesse circulating levels of Anti-Müllerian hormone (AMH) as a predictor of oocyte number and their potential to mature in vitro in both normo-ovulatory (NO) women and in women with Polycystic Ovary Syndrome (PCOS) undergoing in vitro maturation (IVM) treatments. Methods We prospectively studied NO women and women diagnosed with PCOS, (age range 21-39 years) underwent IVM treatments at our center. Serum AMH levels were quantified before each cycle and correlated to oocytes number, maturation and fertilization during in vitro maturation. Results 104 NO and 30 PCOS IVM cycles were followed with retrieval of a total of 672 and 491 oocytes, respectively. In NO women, the serum AMH level positively correlated with the number of oocytes retrieved, (R=0.6; P <0.0001) the number of M2 oocytes at 24 and 48 h (R=0.4; P <0.01; R=0.26 p<0.007, respectively) and with the total number of M2 oocytes (R=0.47; P<0.0001). In the PCOS group, the serum AMH level positively correlated only with the number of oocytes retrieved (R=0.43; P <0.03). Receiver operating characteristic (ROC) analyses showed that a cutoff AMH level of 1.56 (ng/ml) could identify patients with 5 or more oocytes at OPU with a sensitivity of 83 % and a specificity of 75 %. An AMH level of 1.63 (ng/ml) was the threshold for 5 or more matured oocytes (sensitivity=81 %, specificity=53 %). Conclusions Serum AMH may be used as a marker to identify candidates for IVM treatment in both NO and PCOS women.