All animals are populated by microbes, and, contrary to popular belief, most microbes appear highly beneficial to their hosts. They are critical in animal nutrition and immune defense, and they can serve as important catalysts for the effective development and functioning of host tissues. It also is becoming increasingly clear that they can contribute to host behavior. It has been hypothesized that one way they do so is by producing the components of chemical signals that animals use to communicate. We tested and confirmed first predictions of this hypothesis in hyenas, demonstrating that the bacterial and odor profiles of hyena scent secretions covaried and that both profiles varied with characteristics of hyenas known to be communicated through their chemical signals.