Numerous studies have shown the detrimental effects of sperm DNA fragmentation (SDF) on reproductive outcomes under both natural and assisted reproduction conditions. SDF testing has evolved as a valuable adjunct in the evaluation of infertile men, and the rapid development of different SDF assays has improved the perception of its clinical utility. However, normal reference ranges of these assays for male fertility potential are still controversial. In this chapter, the pathophysiological aspects of sperm chromatin and the mechanisms behind SDF are discussed. The implications of SDF on various reproductive outcomes are also presented. Additionally, the SDF-induced male infertility, and the possible genetic consequences and birth defects in offspring are highlighted. Furthermore, a comprehensive analysis of the available SDF assays is provided. Finally, we have discussed clinical scenarios on the application of SDF test and the preventive and therapeutic measures to reduce SDF, and lastly, we discussed the future research opportunities.