Discussion of bioscience ethics requires understanding of the science that underpins biological systems impinging on our lives. Unencumbered by the formal structure of ethics, bioethics presents a forum for discussion of practical matters of individual and collective concern. This comprehensive text is a guide to the essentials of bioscience ethics and an interface between applied science and applied bioethics. Early chapters embrace topics affecting human reproduction – substance abuse and parenthood, aging gametes and congenital malformations, child abuse and its biological consequences. Intermediate chapters deal with end-of-life care and euthanasia, human fertility, assisted reproductive technologies, genetic engineering, and cloning. Remaining chapters challenge human-dominated ecosystems. Population growth, economic activity, and warfare – with its environmental consequences – are reviewed. A background section describes the evolution of ethical consciousness, explores the future, and proposes that the reworking of ethical boundaries can enhance mature decision-making in harmony with changing technology.