The present study explored sex-specific differences in the Big Five factors of personality between different pet ownership groups, in order to understand individual differences in the choice of companion animals. A total of 250 pet owners completed a German version of the NEO-Five Factor Inventory (NEO-FFI). For the first analysis, participants were divided into four broad groups: those owning traditional pets (e.g., cats, dogs), those owning cold-blooded exotic pets, those owning warm-blooded exotic pets, and those not owning animals. For the second analysis, participants were subdivided into nine groups, based on species of animal owned: cats, dogs, birds, fish, reptiles, spider/insect, small mammals, owners of many different animals, and non-owners. In both analyses, separate analyses of variance were applied to the scores of the NEO-FFI scales. Interaction effects between sex and several ownership groups on the traits Openness to Experience and Agreeableness were found in both analyses. Female owners of traditional pets scored, for example, significantly lower on openness to experience than female owners of cold-blooded exotic pets as well as male owners of traditional pets. Furthermore, female owners of cold-blooded exotic pets scored significantly higher on openness to experience than their male counterparts. Regarding agreeableness, male owners of cold-blooded exotic pets scored significantly lower than their female counterparts as well as male owners of traditional pets. These and other results indicate that personality may affect choice of pets but in different directions for the two sexes.