Infertility is a major increasing concern. As the male factor contributes to about half of the infertility cases, sperm analysis is extremely important for diagnosis and investigation of infertility. In this book, the cytometric techniques used to evaluate sperm DNA/chromatin integrity together with some other functional properties of the male gamete are described and advantages and limitations are discussed. In addition, the authors provide an overview of how antioxidative and redox systems participate in spermatogenesis and in pathological conditions, such as heat stress, in the testes. Oxidative stress-induced damage to both oocytes in vivo and embryos in culture are also examined, as well as the role of ROS signalling in embryo development. Furthermore, endometriosis is an oestrogen-dependent disease which affects 6% to 30% of women in reproductive age and is associated with infertility in approximately 60% of cases. In this book, classic and recently proposed etiopathogenic mechanisms or endometriosis-related infertility are discussed, as well as some aspects of its clinical investigation and medical treatment. Other chapters in this book assess the capability of combining of Anti-Mullerian hormone (AMH) and embryo quality as predictors of pregnancy outcome and an examination of how the use of animal models can help us to understand the female reproductive system and the aetiology of some female infertile disorders.