Climbing ability can be a major component of the capability of terrestrial mammals to use vertical habitats. Previous studies suggest that small mammals from central Chile have low climbing capabilities. However, those studies have not disentangled the influence of tree diameter in natural habitats from true climbing ability of different species. We carried out a laboratory experiment by studying the climbing ability of 4 central Chilean small mammals, 2 octodontid rodents (Octodon bridgesi and O. degus), 1 murid rodent (Phyllotis darwini), and 1 marsupial (Thylamys elegans), in situations with different stem diameters. Species showed distinctive climbing abilities. The marsupial T. elegans showed efficient climbing ability independent of stem diameter. P. darwini and O. bridgesi were both influenced by stem diameter, but the former species used smaller-diameter stems less frequently. O. degus showed the lowest climbing ability.