Premature rise of progesterone during the late follicular phase in stimulated IVF cycles is a frequent event and its effect on the endometrial receptivity and on the ART (Assisted Reproductive Technique) - outcome has become a matter of intense debate and research. An emerging body of evidence demonstrates that premature progesterone rise does have a negative impact on the outcome of the ART-success. Until now, the exact cause of progesterone elevation is not fully clear, however lately published studies points to the fact, that premature progesterone elevation might be caused by enhanced FSH stimulation. The impact of elevated peripheral progesterone levels seems to be mainly on the endometrium and the window of implantation, leading to an asynchrony between the endometrium and the developing embryo. Hence, new data show additional an influence on the embryo quality. This review aims to summarize the up-to-date knowledge on the causes of premature progesterone rise during hormonal stimulation, on its influence on endometrial receptivity and embryo quality, on the impact on pregnancy and live birth rates as well as on the possible strategies to prevent this event or to deal with premature progesterone elevation in case it could not be avoided.