The authors aimed to investigate the effect of sildenafil citrate (Sc) on expressions of beta(3) integrin and vascular endothelial growth factor (VEGF), which is taking part in endometrium receptivity in implantation window period in controlled ovarian hyperstimulation (COH) performed rats. In this study, Wistar albino female rats were used and were divided into four groups as control, COH, Sc, and COH + Sc groups. They were sacrificed on the third, fourth, and fifth day of pregnancy, uteruses were resected, and uteri sections were stained with immunohistochemical method and evaluated. beta(3) integrin immunoreactivity was most intensely observed in the endometrial glandular epithelium (GE) and stromal cells in the Sc group on the third day, whereas immunoreactivity was most intensely detected in the luminal epithelium (LE), GE, and stromal cells in the Sc group on the fourth day. VEGF immunoreactivity was most intensely observed in the endometrial LE in the Sc group on the third day, in the Sc and COH + Sc groups on the fourth day, and in the COH + Sc group on the fifth day. Our results indicated that Sc plays a role in both implantation and decidualization by affecting beta(3) integrin and VEGF expressions in implantation window period in rats.