Background: Improvements in IVF have led to an increased number of embryos not available for immediate transfer due to concern about multiple pregnancies. Cryopreservation of supernumerary embryos with subsequent frozen–thawed embryo transfer (FET) is an excellent solution to surplus embryos and has become a common practice in infertility centers. Objectives:The aim of the current work was to evaluate the success rate of hormonal replacement therapy (HRT) and modified natural cycle protocol in frozen–thawed embryo transfer (FET). Patients and methods: Randomized controlled trial study was done at department of Obstetrics and Gynecology, Zagazig University and in a private Center in the period from January 2021 to March 2022. Included 84 women who underwent Frozen-thawed embryo transfer (FET). The women were divided into 2 groups; Natural cycle group included 42 women, 3 of them escaped from the study. Artificial cycle group included 42 women, 2 of them escaped from the study. Result: This study showed that there were no statistically significant differences in the number of embryo thawing, the number of embryo transfers, the degree of embryos, as well as the rate of biochemical and clinical and continuous pregnancy among the studied groups. Conclusion: It could be concluded that both modified natural and artificial cycle for endometrial preparation in frozen-thawed embryo transfer cycles appears to be equally successful about pregnancy rates.