Objectives: Considerable interest has gathered around the possible roles of ME and B-Ep in the regulation of ovarian follicular development and ovulation. This study was to investigate the relationships between ME and B-Ep in the follicular fluid (FF) and serum (S) and their relationships with oocyte maturity.Design: A prospective study.Materials and Methods: FF was obtained from 56 follicles in 16 patients undergoing superovulation and IVF for pelvic adhesions using the same protocol on the day of egg retrieval. Peripheral blood was obtained on the same day. ME, estradiol (E 2 ) and progesterone (P 4 ) were measured in FF and S, while B-Ep in FF only by radioimmunoassays. The mean diameter of each follicle was obtained prior to the follicular aspiration. The oocytes were graded from 1 to 5.Results: Significant positive correlations (P < 0.02) were noted between FF E 2 (141.5 ± 20.1 pg/ml, Mean ± SE) and S ME (15.18 ± 3.62 pg/ml), and FF B-Ep (12.0 ± 0.87 pg/ml); between FF P 4 (5.20 ± 0.52 ng/ml) and FF B-Ep. No correlation was noted between the FF and S samples in ME. Oocyte maturity or follicular diameter was not correlated with either hormones in the FF or S samples. Positive correlation between oocyte maturity and follicular diameter was noted as expected (P = 0.005).Conclusions: Our data show that 1) ovarian steroidogenesis is associated with S ME, and FF B-Ep; 2) intrafollicular ME and B-Ep are not associated with oocyte maturation. The significance of the correlations between FF P 4 and FF B-Ep remains to be investigated.