Guasave (Spanish pronunciation: [ɡwaˈsaβe]) is a city and the seat of the homonymous municipality in the Mexican state of Sinaloa. It is located in the northwestern part of Mexico, southeast of the city of Los Mochis. It stands at 25°34′28″N 108°28′14″W.
In the 2010 census, the city reported a population of 71,196, making it the fourth-largest community in the state, after Culiacán, Mazatlán, and Los Mochis. The municipality has a land area of 3,464.41 km2 (1,337.62 sq mi) and includes many other outlying communities, the largest of which are Juan José Ríos, Gabriel Leyva Solano, and Adolfo Ruiz Cortines. Its biggest local celebration, falls every year on November 12.