Background/Aim: To evaluate a possible lateralization of antral follicle count (AFC) based on the finding that endometriosis, if present, is more commonly found in the left hemipelvis. Methods: We evaluated the records of 6,617 baseline ultrasounds conducted at our Reproductive Center between 2007 and 2011 in a university teaching hospital setting. We included all ultrasounds with an AFC of 1 or greater and excluded those with incomplete documentation or with ovarian cyst, including endometriotic cysts (n = 909). The main outcome measure was the comparison of the number of antral follicles between the right and left ovary. Results: The number of antral follicles in the right ovary (median 18, range 15-22) was significantly higher than in the left ovary (median 16, range 13-20) among women with polycystic ovaries (PCO, AFC ≥24). Similarly, the number of antral follicles in the right ovary (median 8, range 6-10) was significantly higher than in the left ovary (median 7, range 5-9) in women with no PCO but normal ovarian reserve (AFC 10-23). Conclusions: In women with PCO and non-PCO with normal ovarian reserve, the right ovary contains a higher number of antral follicles than the left ovary.