Background: Implantation is proceeded by a process referred as adhesion. Adhesion requires maturation of endometrium and blastocyst to confer adherence ability to them. During IVF cycles, endometrial maturation is facilitated by progesterone administrating. Considering vasodilatory effect of Sildenafild, in genital organs, it appears that Sildenafil may have similar effect as progestrone. The a...