Serum anti-Mullerian hormone (AM H) concentrations constitute a sensitive marker for ovarian ageing. In addition, concentrations of AMH in the follicular fluid constitute a useful marker of embryo implantation in assisted reproduction cycles. The present Study measured serum and follicular-fluid AMH concentrations on the day of oocyte retrieval. These data showed that clinical pregnancy rates (25.0, 34.1 and 42.1%, respectively, P < 0.001). embryo implantation rates (24.3, 35.0 and 44.4%, respectively, P<0.001) and fertilization rates (59.2, 70.9 and 79.5%, respectively, P < 0.001) were markedly different among the low, moderate and high follicular-fluid AMH groups but not among the different serum AMH concentration groups. Follicular-fluid AMH concentrations were negatively correlated with follicular-fluid oestradiol concentrations. The results of this study suggest that follicular-fluid AMH concentration on the day of oocyte retrieval would appear to better reflect the reproductive outcome in PCOS patients undergoing assisted reproduction.