Abstract: Objective：To investigate whether women with high risks of ovarian hyperstimulation syndrome （OHSS） undergoing controlled ovarian hyperstimulation have the altered levels of the luteinizing hormone/choriogonadotropin receptor （LHCGR） mRNA in the lymphocytes. Methods：In this single center prospective study，108 IVF-ET patients were divided into 3 groups according ovarian response. In 42 cases with high OHSS risks，those 19 cases diagnosed OHSS were group A，the others 23 cases were group B. Those 62 cases with normal ovarian response were group C. The levels of LHCGR mRNA in lymphocytes were detected by PCR technology in the days of hCG injection and ovum pick-up （OPU day）. Results：The level of basal serum FSH in group A was lower than that in group C （P=0.028）. The serum concentration of estradiol （E2） in both group A and group B was higher than that in group C on the days of hCG injection and OPU（P=0.000）. The median numbers of oocytes retrieved per patient in group A and group B were more than that in group C （P=0.000）. Group A had higher expression of LHCGR in lymphocytes mRNA on the hCG day and OPU day than group B and group C（P＜0.05）. The difference of the levels of LHCGR mRNA in lymphocytes between group B and group C was not significant（P＞0.05）. Conclusions：Expression of LHCGR mRNA in lymphocytes was related to ovarian response， which increased in OHSS patients. It could be used as a marker to predict OHSS.

Key words: Chorionic gonadotropin, Ovarian hyperstimulation syndrome, Fertilization in vitro, Embryo transfer, Polymerase chain reaction