The chapter discusses the decline in male reproductive health, including declining semen quality, increasing testicular cancer incidence, and rising rates of hypospadias and cryptorchidism, over the past few decades. These trends are observed in many countries and are associated with geographic differences. The authors suggest that exposure to environmental chemicals with estrogenic activity, known as xenoestrogens, may be a contributing factor. These chemicals can affect fetal and childhood development, potentially leading to adverse reproductive outcomes. The chapter also reviews the impact of xenoestrogens on wildlife, including changes in sexual differentiation, reduced fertility, and altered behavior. It highlights the need for further research to understand the extent and mechanisms of these effects and to develop strategies for prevention and intervention.The chapter discusses the decline in male reproductive health, including declining semen quality, increasing testicular cancer incidence, and rising rates of hypospadias and cryptorchidism, over the past few decades. These trends are observed in many countries and are associated with geographic differences. The authors suggest that exposure to environmental chemicals with estrogenic activity, known as xenoestrogens, may be a contributing factor. These chemicals can affect fetal and childhood development, potentially leading to adverse reproductive outcomes. The chapter also reviews the impact of xenoestrogens on wildlife, including changes in sexual differentiation, reduced fertility, and altered behavior. It highlights the need for further research to understand the extent and mechanisms of these effects and to develop strategies for prevention and intervention.