Mammals from the state of Guerrero, Mexico, are poorly studied, particularly those from the Balsas River basin, despite the importance of this area as a biogeographical boundary for flora and fauna. To contribute to the knowledge of mammals in this state, we compiled information on geographical distribution, habitat, and reproduction for 41 mammal species from Tlaxmalac in the Balsas River basin in northeastern Guerrero. These represented 26.9% of mammal species known from Guerrero and 8.6% of mammal species from Mexico. Eight species were endemic, comprising 19.5% of species surveyed. Mammals from Tlaxmalac had eight different feeding habits. People from the community use 14 species of mammals as part of their diet, as pets, for medicinal purposes, and other uses. Overall, Tlaxmalac supports a great diversity of small and medium-sized mammals.