Several factors are related to sperm DNA damage and not all mechanism are known. Multiple sources have been proposed including abortive apoptosis, abnormal chromatin packaging during the transition from round to elongated spermatids and oxidative stress. Moreover, many enviromental conditions are related to reproductive toxicity, including structural and functional alterations of human sperm and particularly sperm DNA damage. Finally, several evidences suggest that infiammation/infection in the male reproductive tract may impair fertility leading to improve of DNA fragmentation. In the last years, several evidences showed like sperm DNA damage may to related to infertility leading to the insight that the assessment of sperm DNA integrity could be considered a potential new semen quality biomarker.