Most reviews addressing the ethics of animal research describe this debate as a war of wills between scientists and animal rights activists. Ethical arguments favoring animal experimentation generally fall into two categories: humans have higher moral standing than animals and have a right to use animals in experiments that better human lives, and the benefits of animal experimentation outweigh the harms, and that animal experimentation is sometimes the only way in which science can answer important questions necessary to human well-being. Mainstream scientific study has now challenged long-held beliefs that animals are fundamentally different than humans in many morally relevant ways. The 3Rs of animal research ethics: replace, reduce, and refine have been adopted internationally in legislation and regulations regarding animal research. Animal researchers have ethical obligations to seek alternative models whenever possible, to offer humane care that reduces pain,distress and harm when using animals in research.