Objective To observe the effect of Yiqi Yangyin Formula on oocyte quality and pregnancy outcome in poor ovarian response（ POR） patients with in vitro fertilization and embryo transfer（ IVF-ET） and discuss the possible mechanism. Methods In total 59 POR patients with the history of IVF-ET were randomly divided into a treatment group with 28 cases and a control group with 31 cases. Both groups adopted the Minimal Stimulation IVF（ MiniIVF）

and the treatment group was also administered with Yiqi Yangyin Formula one dose daily from the second day of the menstrual cycle in the month when the control ovarian hyperstimulation started until the day when the patients were injected with human chorionic gonadotropin（ HCG）. Retrieved oocytes and pregnancy outcomes between the two groups were compared. The usage of Gn during tropic hyper ovulation

sex hormone levels and endometrial thickness in both groups were observed. Also

the expression of growth differentiation factor-9（ GDF-9） and bone morphogenetic protein-15（ BMP-15） in granulosa cell in follicle fluid from patients were detected. Results The average number of retrieved oocytes

fertilization rate

optimal embryo rate

clinical pregnancy rate in oocyte retrieval cycles were4. 51 ± 2. 49

51. 93%

47. 19% and 23. 81% in the treatment group

and 2. 02 ± 1. 98

46. 90%

42. 42%

and 10. 42% in the control group

respectively. There were significant differences in the number of retrieved oocytes and clinical pregnancy rate between the two groups（ P < 0. 05）

while no statistical differences showed in fertilization rate and optimal embryo rate between the two groups（ P > 0. 05）. Compared with those in the control group

the usage of Gn was less

the estradiol levels

the endometrial thickness

and the expression of GDF-9 and BMP-15 were higher in the treatment group

with significant differences between the two groups（ P < 0. 05）. Conclusion Yiqi Yangyin Formula could improve the ovarian response in POR patients in the process of IVF-ET

and increase the number of retrieved oocytes and pregnancy rate. The possible mechanism might be related with regulating the expression of GDF-9 and BMP-15 in ovarian granulosa cells.