An ethnobotany study in collaboration with Q'eqchi' Maya healers of Southern Belize led to a collection of 169 medicinal plant species, belonging to 67 different families. The data show the use of a majority of species from primary or secondary semi-evergreen rainforests of Southern Belize, rather than weedy species. The medicinal uses of the plants were grouped into 17 usage categories. The frequency of use for each plant and the informant consensus factor for each usage category reveals a consensus among the healers on the use of plant species as well as on the diseases treated. These results suggest a well-defined medicinal tradition.