The theory of evolution has been used in arguments regarding animal experimentation. Two such arguments are analyzed, one against and one in favor. Each argument stresses the relevance of the theory of evolution to normative ethics but attempts explicitly to avoid the so-called naturalistic fallacy. According to the argument against animal experimentation, the theory of evolution 'undermines' the idea of a special human dignity and supports 'moral individualism'. The latter view implies that if it is wrong to use humans in experiments, then it is also wrong to use animals, unless there are relevant differences between them that justify a difference in treatment. No such differences can be found with regard to animals which lead 'biographical lives'. The argument in favor of animal experimentation is based on evolutionary psychology. It states that humans, as all social animals, are speciesist by nature and stresses that this should be taken seriously in normative ethics. This does not mean that animal interests should not be considered, only that vital human interests may outweigh them. In order to assess the arguments, one has to take a stand on certain more basic issues: 'is' versus 'ought', impartiality versus special obligations, and feelings/intuitions versus reason. Given the author's own position with regard to these more basic considerations, the-evolutionary argument in favor of animal experimentation is judged to be more convincing than the one against but not decisive. It is also maintained that not all animal experiments are acceptable. Which animal experiments are acceptable and which are not has to be decided on a case-by-case basis.