This research paper presents findings from an experimental investigation of the attitudes that people hold towards animals when they are reminded of the fact that humans and animals are creatures alike. We tested the hypothesis that mortality salience (MS) would lead participants reminded of human creatureliness to evaluate animals more negatively, especially when they reported lower self-esteem. Student participants were randomly assigned to conditions in which MS was made salient and thoughts about human creatureliness were manipulated. Participants then reported their attitudes towards animals. Lending support to the hypothesis of this study, MS led participants with lower self-esteem to rate animals more negatively, when they were reminded of human-animal similarity. The implications of these results for understanding people's attitudes towards animals were discussed.