Background: Anti-Mullerian hormone (AMH) is a member of the transforming growth factor-β superfamily. It may play an important role in the ovarian folliculogenesis. Objective: To study the relationship of AMH and some clinical, endocrinal and ultrasound parameters in anovulatory infertile women with polycystic ovary syndrome (PCOS) and in women with normal menstrual cycles. Methods: Sera were collected from 30 PCOS anovulatory women and from 15 normal women during the early follicular phase "day 3" of the menstrual cycle, stored frozen until assayed. Results: Serum AMH concentrations were significantly (P<0.001) elevated in PCOS women (9.55±3.39 μg/liter) compared with controls (2.33±1.8 μg/liter). In PCOS patients, serum levels of AMH were correlated with features characteristics of PCOS such as LH concentrations (r=0.76, P<0.001), testosterone level (r=0.67, P<0.001), mean number of follicles (r=0.68, P<0.001) and ovarian volume (r=0.54, P<0.001). Also, AMH levels were correlated with age (r=-0.51, P<0.001) and with cycle duration (r=0.46, P<0.001). The correlation between AMH levels and FSH, estradiol or BMI were found statistically non significant. Conclusion: The present study provides evidence that serum levels of AMH is elevated in PCOS patients. This may have a role in the disordered folliculogenesis characteristics of that disease.