Objective: this study was effects of endometrial and subendometrial blood perfusion and endometrial volume on endometrial receptivity in frozen embryo transfer (FET) cycles. Materials and methods: This prospective observational cohort study, that on infertile women who referred for FET to Shariati Hospital and Omid Infertility Clinic in Tehran (Iran) .112 patients selected among eligible women with good quality embryos. After homogenization, participants underwent endometrial preparation for hormone replacement therapy (HRT) according to a similar routine protocol. On the day of the FET, they underwent a thorough ultrasound examination for possible effective parameters. Subsequently, one to two good quality blastocysts were transferred, and the pregnancy outcomes were monitored. Results: In vitro fertilization (IVF) was performed on 112 patients with a mean age of 33.93±4.93 years. Although, serum β-HCG level was used to confirm pregnancy. Accordingly, out of 112 participating patients, 50 (44.6%) became pregnant after IVF. Based on the results of this study, the endometrial blood flow was significantly different between the two groups of pregnant and non-pregnant women, so that a higher pregnancy rate was observed in participants with multi-focal and spare endometrial blood flows (P<0.05). Additionally, a significant relationship between endometrial blood flow and pregnancy outcome so that there was more ongoing pregnancy rates in those with multi-focal and spare endometrial blood flows (P<0.05). But the endometrial variables of volume, length, width, thickness and pattern were not significantly different between the two groups of pregnant and non-pregnant women. Moreover, contextual parameters had no significant relationship with pregnancy outcome (P>0.05). Endometrial measurement indices were also ineffective on pregnancy outcomes and no significant difference was there between the groups (P>0.05). Conclusion: Collectively, the endometrial blood flow can play an effective role in improving pregnancy event and its stability after IVF, but the endometrial volume was unable to predict pregnancy event and its stability after IVF.