The mesquite mouse (Peromyscus merriami), also known as Merriam's deermouse, is a species of rodent in the family Cricetidae found in Mexico and Arizona, United States.
The mesquite mouse can be found in south-central Arizona in the United States and in Sonora and Sinaloa in Mexico. It occurs in areas of dense brush and mesquite bosque in riparian and desert habitats from sea level up to .