In research employing animals we commonly do things to them which would be grossly immoral to do to humans. This paper discusses three possible justifications for so treating animals: (a) it is violating the autonomy of rational beings which makes actions immoral, and animals are not autonomous; (b) due to our participation in the human community, we have special obligations to humans that we do not have to animals; and (c) human life is morally more worthy than animal life. The conclusion of this discussion is that none of these three propositions justifies the routine sacrifice of animal interests for human benefit. Particular attention is paid to the idea that human life is morally more worthy than animal life, because I believe that to be the most common justification for our sacrifice of animal interests in research. The claim of greater worth is considered and criticized from both utilitarian and Kantian perspectives, and the inference from superior worth to being entitled to exploit one's inferiors is also criticized. The paper concludes by recommending a governing principle for research with animals which would bring that research into line with the rejection of hierarchical worldviews, social orders, and value systems which characterizes modern moral progress.