Abstract: Human chorionic gonadotropin（hCG） is produced by placental syneytiotrophoblast. Human urinary u-hCG and recombinant hCG， were now widely administered in assistant reproductive technique（ＡＲＴ）. Recently， the embryo quality and clinical outcomes were improved by using hCG for pretreatment before IVF/ICSI cycles. hCG can be used for completing cotrolled ovarian stimulation in late follicular phase as a substitution of LH or FSH in both long?-protocol and antagonist-protocol， and for enhancing embryo invasion by immunologic mechanism. Generally， hCG plays an irreplaceable role in the clinic of ART.

Key words: Chorionic gonadotropin, Reproductive techniques, assisted, Follicular phase, Autoimmunity