In this chapter 5, we introduce animal ethics and different views on the ethical permissibility of animal experimentation. The chapter highlights two aspects of discussions on animal experimentation ethics can, namely, the moral status of other-than-human animals and the moral theories, consequentialism and deontology, on which the argumentation is built. Along these dimensions, we provide students and researchers with a brief overview of some arguments in favor or against animal experimentation. Finally, we also lay out the hybrid approach to animal experimentation ethics, which underpins current evaluation policies and EU regulation on the ethical acceptability of animal studies.