The Janos Biosphere Reserve (Spanish: Reserva de la Biosfera de Janos) is a nature reserve in Janos, Chihuahua, Mexico. It protects a prairie ecosystem best known for its recovering and reintroduced species most notably the herd of American bison (Bison bison) which became the first re-established in Mexico. It is the first federally protected area of Mexico with the main objective of protecting a grassland ecosystem.