Members of the class Mammalia have the most advanced skeletal complexity of the nasal cavity among vertebrates. Most mammals have an olfactory epithelium that consists of basal cells, supporting cells and olfactory sensory neurons that bind odor molecules with their cilia. The olfactory epithelium is responsible for detecting odor stimuli. The surface area of olfactory epithelium varies greatly among species. Carnivores have a generally larger surface area of the olfactory epithelium than primates and ungulates of the same size. Modern odontocetes lack olfactory epithelium. To get an overview of the between-species differences of the olfactory epithelium surface area and number of olfactory receptor cells, a search of the scientific literature was performed, using the database Web of Science and references from the scientific articles. The assembled data were entered into two tables, one that contains species names, surface area of the olfactory epithelium and references, and another that includes the total number of olfactory receptor cells for the few species that have been studied in this respect so far. Methods of measuring olfactory epithelium size differ, some studies used immunohistochemistry, other measured osteological proportions, like the surface area of the olfactory turbinals. A compilation of the published data provides an overview of the range that the size of the olfactory epithelium can have and allows for between-species comparisons of this anatomical measure as well as for assessing possible correlations with olfactory capabilities.