Many people in the animal welfare communityhave argued that the use of nonhuman animals inmedical research is necessarily based onspeciesism, an unjustified prejudice based onspecies membership. As such it is morally akinto racism and sexism. This is misguided. Thecombined capacities for autonomy and sentiencewith the obligations derived from relationssupport a morally justifiable rationale forusing some nonhuman animals in order to limitthe risk of harm to humans. There may be a fewcases where it is morally better to use a neversentient human than a sentient animal, butthese cases are few and would not fulfill thecurrent need for research subjects. The use ofnonautonomous animals instead of humans inrisky research can be based on solid moralground. It is not necessarily speciesism.