Peromyscus boylii (Baird, 1855), the brush deermouse, is a common cricetid rodent in the southwestern United States and Mexico. It is a member of the Peromyscus boylii species group and has had a complicated taxonomic history because many former subspecies have been elevated to species. It is a medium-sized Peromyscus with small ears and a long, slightly bicolored and slightly haired tail that ends in a tuft of long hairs. It prefers brushy habitat, showing an affinity for oak–scrub oak and canyon–creek bottoms. It is not of special conservation concern.