Although some previous studies (2, 20-24), in line with our study, indicated nosignificant variation in pregnancy proportions with letrozole application,Piedimonte et al. (25) indicated that pregnancy and live-birth rates increasedsignificantly following administration of a letrozole and GnRH agonist combination.Given the varied findings of previous studies, future studies seem needed to assessthe effect of varying doses of letrozole in infertile women with endometriosis, aswell as to compare the effect of a combination of letrozole with agonist vs.antagonist IVF protocol. Here, GNRH1 is linked to endometriosis.