Peromyscus mexicanus (Saussure, 1860) is a medium-sized cricetid commonly called the Mexican deermouse. It is 1 of 56 species but can be readily distinguished from nearly all other species of Peromyscus by the near absence of hair on the tail. It is found from the tropical lowlands of Mexico to Panama and it exhibits geographic and seasonal variation in coat color. Its preferred habitat includes forested regions where it is often found in burrows beneath fallen logs and among the underbrush and roots of trees. P. mexicanus prefers deep forest to edge forest. The Mexican government does not consider this species as endangered. DOI: 10.1644/858.1.