Aromatase inhibitors (AI) prevent the enzymatic conversion of androgens to estrogens. This significantly lowers serum estrogen levels. AI have been administered around the time of menses for ovulation induction and ovulation was seen to follow 10 to 12 days later. The rationale for inducing atresia of dominant follicles stems from this observation. Acute estradiol deprivation should theoretically initiate atresia of all viable follicles in the cohort resulting in the emergence of a new follicle wave without an ovulation event occurring.