Background: On the basis of recent review articles, there was no evidence that miscarriage was influenced by intra-cavity human chorionic gonadotropin (IC-hCG) administration, ir-respective of embryo stage at transfer or dose of IC-hCG and well-designed multicenter trials are required to provide robust evidence. The present study was conducted to assess the influ-ence IC-hCG infusion before embryo transfer on the clinical pregnancy and live birth rates after vitrified-warmed embryo transfer (ET) in programmed cycles.Materials and Methods: This study was a single-blind rand-omized clinical trial for eligible patients underwent frozen ET cycles with long-term hormonal GnRH agonist protocol for endometrial preparation. Immediately prior to ET, the women were randomly divided into three groups. In the experimental group, 7-10 minutes before embryo transfer, 500 IU of hCG with a 40 μL of culture medium was injected into the uterus. In the first control (sham) group, 7-10 minutes before ET just 40 μL of culture medium intrauterine was infused. In the second control group, no intervention was done. The pregnancy out-comes were compared in the three groups by using appropriate statistical tests.Results: Finally 180 patients allocated into three groups. There was no significant difference in terms of patients ‘characteris-tics among three groups. No significant difference was found in terms of clinical pregnancy among three groups. The miscar-riage rate in control group (0%) was significantly lower than those of in the sham and hCG groups (9.8% and P=0.01, 6.6% and P=0.04, respectively). Also, live birth rate (39.3%) in con-trol group was significantly higher than those of in the sham and hCG groups (16.4% and P=0.005, 23% and P=0.051, re-spectively).Conclusion: It was found that intrauterine injection of 500 IU hCG before vitrified-warmed ET at cleavage stage has no beneficial effect on pregnancy outcome and is not suggested. (NCT02355925)