Factors that may explain a low oocyte recovery rate by laparoscopy were examined. Two different groups of women were evaluated. Group A (n = 56) had zero or one oocyte recovered, despite the aspiration of three or more follicles. Group B (n = 36), had oocytes recovered from more than 75% of punctured follicles. Group B showed significant increases in total estradiol (E2) values during the follicular phase (P less than .05), E2 peak levels (P less than .001), and number of patients with E2 rise the day after hCG administration (P less than .001) compared with group A. However, the number and size of the follicles as determined by ultrasound during the last two pre-oocyte recovery days were not significantly different. On the day of laparoscopy, there was a significant decrease in the number of follicles in group A versus B (P less than .001). In addition, the number of patients with a decrease in E2 values the day of laparoscopy was significantly higher in group A (P less than .001). Together these factors suggest an increased incidence of ovulation prior to laparoscopy in group A. The extent and severity of adhesions were graded as absent, mild or moderate, and severe. No difference was observed between groups. Moreover, comparing the number of follicles visualized before laparoscopy and the number of follicles punctured, the ovarian accessibility was not different (76.6% vs. 79.5%). This suggests that a decrease in access to the ovaries was not the cause of poor oocyte recovery. It is concluded that differences in recovery rates, then, are best attributed to the endocrine milieu of the cycle.