Objective To investigate the effect and the possible mechanism of Gutai Decoction on outcome of pregnancy after in vitro fertilization and embryo transfer（ IVF-ET） in patients with repeated embryo transfer failure.Methods One hundred and twenty patients with 2 times or more unsuccessful IVF-ET were randomly divided into a treatment group（ 60 cases） and a control group（ 60 cases）. Both groups were given 40

80 mg of progesterone injection every day since two days before transplantation. The treatment group was also given Gutai Decoction orally

one dose per day

taking both in the morning and evening

for three consecutive menstrual cycles. The implantation rate

the clinical pregnancy rate

and the pregnancy outcome in the two groups were analyzed. Twelve days and 3 weeks after transplantation

serum levels of progesterone（ P）

human chorionic gonadotropin-β（ β-HCG）

basal follicle stimulating hormone（ FSH）

and estradiol（ E2） in successful implantation patients in the two groups were tested.Results Implantation rate was 71. 7%

the clinical pregnancy rate was 63. 3%

the abortion rate was 10. 5%

and the full-term live infant rate was 84. 2% in the treatment group; while those corresponded in the control group were56. 7%

45. 0%

29. 6%

and 59. 3% respectively. The implantation rate

the clinical pregnancy rate and the fullterm live infant rate in the treatment group were higher than those in the control group

and the abortion rate was lower than that in the control group（ P

<

0. 05）. Three weeks after implantation

the levels of P

β-HCG and E2 in the successful implantation patients in both the two groups were significantly higher than those 12 days after implantation

and the level of FSH significantly lower than that 12 days after implantation（ P

<

0. 05）; three weeks after implantation

the levels of P

β-HCG and E2 in successful implantation patients in the treatment group were significantly higher than those in the control group

and the level of FSH significantly lower than that in the control group（ P

<

0. 05）. Conclusion Gutai Decoction could improve clinical pregnancy rate and reduce abortion rate in patients with repeated embryo transfer failure. The mechanism may be associated with increasing levels of P

β-HCG

and E2

and decreasing level of FSH.