Prolonged sperm-storage is an adaptation to the reproductive cycle that is most highly developed in bat. Twenty four bat species have been identified so far to store spermatozoa for the period of approx. 16 days up to ~225 days and still retain fertilizing capacity. The aim of this review is to evaluate the mechanism and molecules necessary for sperm to become efficiently stored in female genital tract. Spermatozoa are arranged with their head towards the reproductive tract epithelium are characterized in all sperm storing bat species so far investigated, suggesting that such intimate relationships are an integral part of the mechanism of prolonged storage of sperm. Recent study suggests that the ultimate controls of the mechanism underlying spermstorage are hormonal. It has been demonstrated that sperm stored in female bat contains high circulating level of androgen during the period of sperm storage. It is suggested that androgen creates a unique microenvironment that facilitates prolonged sperm storage. The identification of the specific molecules responsible for prolonged spermstorage may suggest a mechanism to keep the sperm viable for prolonged period for use in assisted reproductive technique.