Selenium is essential for normal spermatogenesis of mammals and its critical role is mainly mediated by two selenoproteins, namely phospholipid hydroperoxide glutathione peroxidase (PHGPx/GPx4) and Selenoprotein P. PHGPx/GPx4 is the major selenoprotein expressed by germ cells in the testis, having multiple functions and representing the pivotal link between selenium, sperm quality and male fertility. Selenoprotein P is a plasma protein that is required for selenium supply to the testis. In the last years, nutritional studies and experimental animal models lacking/overexpressing a specific PHGPx isoform and selenoprotein P have highly expanded our understanding on how the male reproductive system depends on selenium. The focus of this review, is to report and discuss the most relevant and recent findings in this field. Clinical data have pointed to a correlation between abnormal PHGPx content in sperm and disturbance of human male fertility. However, additional evidence is still required to draw any definitive conclusions about therapeutical strategies for improving fertility by selenium administration.