Abstract: Objective: To investigate the clinical effectiveness of Zuogui pill, a Chinese medicine, for those infertility women with recurrent implantation failure（ＲＩＦ）. Methods：Eighty infertility women with RIF were selected, who took frozen-thawed embryo transfer （ＦＥＴ） cycles with GnRHa down-regulation protocol. Patients were randomly divided into two groups: The Chinese medicine group was treated with Zuogui pill, a Chinese medicine （ｎ＝４０）, during down-regulation for 4 cycles, while the control group without Chinese medicine during their cycles (n=40). The pregnancy rate, the levels of serum hormones, the echo of EMI and endometrial blood flow under B ultrasound were assessed. Results：The levels of serum E2, LH and P on the day of hCG administation were not significantly different between the Chinese medicine group and the control group （P＞0.05）. The clinical pregnancy rate and the level of serum E2 in the group treated with Zuogui pill were significantly higher than those in the control group （Ｐ＜０．０５）. Compared with control group, the Chinese medicine group had better endometrial blood flow RI and echo of EMI（Ｐ＜０．０５）, and no significant changes in blood flow PI and blood branches of endometrium （Ｐ＞０．０５）. Meanwhile, the adverse reaction in the Chinese medicine group, such as hot flashes and weakness of the lumbar region, were lower (P＜0.05). Conclusions：Our data showed that the Zuogui pill may be benefit for the treatment of RIF, with balance of serum hormones, improvement of endometrial blood flow, and the improved clinical outcomes.

Key words: Reproductive techniques, assisted, Embryo transfer, Zuogui pill, Recurrent implantation failure, Frozen-thawed embryo transfer