Abstract: Objective：To explore the effects of two criteria of hCG administration on the clinical outcomes of IVF/ICSI-ET. These criteria were individually based on the follicle diameter and the follicle symmetry. Methods：It′s a prospective randomized study in our hospital reproductive center. IVF/ICSI-ET patients were randomly divided into two groups from Jan 2013 to Mar 2013. The criterion of hCG administration in Group A was based on the follicle diameter，while Group B on the follicle symmetry. Clinical and laboratory outcomes were then compared. Results：The average days of Gn, serum levels of progesterone and estradiol on the hCG day，the average number of matured eggs, and the rate of matured oocytes of group B were significantly higher than those of group A（P＜0.05）. There was not significant difference in the numbers of frozen embryos and good quality embryos between the two groups. However，the clinical pregnancy rate of group B was significantly lower than that of group A（42.19% vs. 54.22%， χ2＝4.18，P＝0.04）, and the incidence of OHSS in group B significantly higher than that of group A（10.77% vs. 5.86%， χ2＝4.07，P＝0.04）. Conclusions：The criterion based on the uniform size of follicular is not superior to the traditional criterion focused on the dominant follicle size in the efficacy and safety of IVF/ICSI-ET treatment.

Key words: Chorionic gonadotropin, Fertilization in vitro, Sperm injections, intracytoplasmic, Embryo transfer, Superovulation, Pregnancy outcome