Sperm motility is a key function in the process of fertilization. Significant gaps in the knowledge of the mechanisms of control and modulation of sperm motility still remain. It is well known that the percentage of motile sperm is correlated with fertility in vivo but the recent development of assisted reproductive technologies and the extensive use of objective methods to assess sperm movement in vitro indicate that the quality of sperm movement is important too for fertilization. However, the exact pattern of motility characteristics to fulfill fertilization in vitro and in vivo are not clearly established essentially because of the lack of multiparametric and controlled studies in vitro and prospective studies in vivo. There is also presently no evidence for an improvement of fertility when using different pharmacological approaches to increase sperm motility in vitro. Therefore, further efforts are required to improve our basic knowledge of the relations between sperm motility and fertility with the aim to adapt and apply it to the problem of male infertility.