This chapter describes the existing knowledge regarding the ideal molecular profile of sperm cells, in order to define the model to be mimicked when stem cells are employed in order to create male gametes. Sperm production is defective in a significant proportion of males aiming at fatherhood. Interestingly, there are a significant proportion of infertile males presenting normal sperm counts, thus diagnosed as having idiopathic infertility. To date, there are a lot of studies concerning DNA analysis of human spermatozoa suggesting that the determination of DNA fragmentation levels can be a parameter of semen quality, directly implicated in male fertility. Sperm membrane lipid composition is of special interest, given their involvement in fertilization, capacitation, spermatozoa, and oocyte interaction. The future vision shows the possibility to create sperm cells from adult stem cells, with all the requirements to succeed fulfilled, thus guaranteeing a safe and successful use.