Abstract: Ovarian hyperstimulation syndrome（OHSS） is an exogenous or endogenous gonadotropin-induced syndrome. OHSS is associated mainly with exogenous gonadotropin，occasionally with Clomiphene，rarely with the natural cycles of pregnancy. In recent years，with the increasing incidence of anovulatory infertility，the controlled ovarian hyperstimulation becomes a necessary step in in vitro fertilization and embryo transfer. OHSS gradually became one of the most common complications with potentially high-dangerous in assisted reproductive technology. OHSS affects embryo implantation and embryo development, and it could be fatal in some severe cases. The research progress on the pathogenesis，clinical manifestations，prevention and treatment of OHSS were discussed in this review.

Key words: Ovarian hyperstimulation syndrome, Gonadotropins, Ovulation induction, Fertilization in vitro, Embryo transfer, Reproductive techniques, assisted