 RANKL, RANK and OPG are expressed in the testis and this pathway appears to be a novel regulator of germ cell proliferation. Decreased semen quality is a major factor of male infertility. Semen quality is a measure of the ability of the sperm to accomplish fertilization. Evaluation of male fertility potential is today basically conducted through semen analysis. There is no treatment for men with no sperm in the ejaculate and there exist no drug that can increase sperm counts.Therefore, drugs that can lower RANKL expressionactivity for instance an antibody against RANKL such as Denosumab may be used for this new indication: A new treatment option of infertile men with impaired semen quality. 