Drawing from an existential perspective rooted in terror management theory, four studies examined the hypothesis that breast-feeding women serve as reminders of the physical, animal nature of humanity and that such recognition is threatening in the face of one's unalterable mortality. Study 1 demonstrated that mortality salience (MS) led to more negative reactions toward a scenario depicting a woman breast-feeding her infant in public, and in Study 2, MS decreased liking and increased physical avoidance of a potential task partner described as breast-feeding in another room. Further supporting the hypothesis that such reactions are rooted in threats associated with human creatureliness, MS in conjunction with a breast-feeding prime led to an increase in the accessibility of creaturely related cognitions (Study 3) and priming human/animal similarities (i.e., creatureliness) led to increased negativity toward a magazine cover depicting a woman breast-feeding her child (Study 4). Implications of this research are discussed.