Taking Letrozole tablets continuously for 5 days will usually result in ovulation about 3-7 days after stopping, but there may be individual differences from woman to woman. The main effect of letrozole is to promote follicle development and can be used in women who have immature follicles and are unable to ovulate normally. Ovulation usually occurs in the vast majority of women around 3-7 days after discontinuation of letrozole tablets, which are usually started on the 5th day of menstruation. Generally speaking, when the follicle diameter is >1.8cm or more, it is a mature follicle, but it needs to be detected by ultrasound, and when the follicle is mature, it may ovulate on its own. However, in patients with polycystic ovary syndrome, they may not be able to ovulate on their own and need to be assisted with ovulation by human chorionic gonadotropin injection. It should be noted that letrozole ovulation treatment should be used under medical supervision, as improper use of the drug may lead to ovarian hyperstimulation with serious consequences, even leading to premature ovarian failure.