Native ungulate species constitute an important source of protein for Mesoamerican subsistence hunters. In this study, we (1) provide evidence supporting the hypothesis that source-sink systems help maintain some of the ungulate populations in the Lacandon Forest, Mexico; and (2) test the assumptions that density, age structure, and sex ratios are different in slightly hunted (potential sources) and persistently hunted (potential sinks) populations. From May 1998 to March 2001 we observed 1144 individuals and 1153 tracks of five ungulate species (Baird's tapir, collared peccary, white-lipped peccary, red brocket deer, and white-tailed deer) along 1908 km of line transects in slightly and persistently hunted sites of Montes Azules Biosphere Reserve (MABR) and adjacent community lands. Densities of Baird's tapir and white-lipped peccary were lower in persistently hunted sites, where there were higher proportions of young tapirs and white-tailed deer. The sustainability of hunting was evaluated in five communities using information on harvest rates, production rates, and density of each population. Our results suggest that persistently hunted populations of Baird's tapir and white-lipped peccary are at risk of local extinction, while collared peccary hunting appears to be sustainable. The red brocket deer, although locally overhunted, maintains a relatively safe status probably through a source-sink system in which MABR functions as the source of individuals which are readily hunted in adjacent community lands. Source-sink systems may be also important in maintaining Baird's tapir and white-lipped peccary populations outside protected areas of the Lacandon Forest, from evidence of migration observed during this study. © 2007 Elsevier Ltd. All rights reserved.