Chorionic gonadotropin (CG), as a embryonic factor, controls the implantation process and pregnancy formation. The hormone regulates endometrial functions by its influence on progesterone production and direct modulation of endometrial cell functions. Recent studies suggest the key role of CG in controlling the main implantation processes like apoptosis, angiogenesis, maternal immunological response and trophoblast migration. The review of recent studies regarding CG function indicates its pivotal role in embryo implantation and suggests possible medical applications.