Abstract: Objective：To investigate the effects of two methods of endometrium preparation for froze-thawed embryos transfer（FET）, using natural cycle and hormone replacement therapy. Methods：111 cycles of ＦＥＴ were retrospectively analyzed. Those cycles were divided into two groups：the natural cycle group （69 cases）, and the hormone replacement group （４２ ｃａｓｅｓ）. The clinical parameters were compared between the two groups, including age, infertility duration, the number of thawed embryo, the number of transplanted embryo, the number of high-quality post-implantation embryo, endometrial thickness on the day of endometrial transformation, embryo implantation rate, clinical pregnancy rates and early abortion rate. Results：There were no significant differences between the two groups in age, infertility duration, the number of thawed embryo, the number of transplanted embryo, the number of high-quality post-implantation embryo, endometrial thickness on the day of endometrial transformation, clinical pregnancy rate, embryo implantation rate and early abortion rate（P＞0.05）. Conclusions：There are same pregnancy outcomes using the two ways of endometrium preparation for FET. The way to prepare endometrium for those FET patients should be taken individually.

Key words: Cryopreservation, Embryo transfer, Menstrual cycle, Hormone replacement therapy, Pregnancy outcome