The Sierra San Antonio is a mountain range in the northern pard of the Mexican state of Sonora.

The approximately 10 miles (16 km) long range is the southern section of the Patagonia Mountains, which lie in Arizona.

Two miles (3.2 km) north of the border and the Sierra San Antonio is Mount Washington at 7,221 ft (2,201 m), the highest peak of the Patagonia Mountains.

Various species are studied in the Madrean Sky Islands habitats in higher elevation mountains of northern Sonora and Chihuahua, southeast Arizona, and southwestern New Mexico.

One example is research on horned lizards in mountainous areas in northern Mexico in various mountain ranges, including the Sierra San Luis range to the east.