Sperm cells evolved to acquire a sophisticated motility structure called a flagellum which gives spermatozoa a self-propelling force. Nonetheless, in internal fertilizing species such as mammals, the length and complexity of the female genital tract mean that sperm motility is insufficient to accomplish the sperm’s mission of transferring genetic material to the oocyte. Thus, a long-standing question in the reproductive biology field has been how spermatozoa are delivered to the oocyte surface. Several mechanisms have been proposed to help sperm transport, such as oviduct peristalsis, chemotaxis, thermotaxis and rheotaxis. In this chapter we will discuss the state of the art of sperm chemotaxis.