The presence of feral goats can have detrimental effects to insular ecosystems where native plants have evolved in the absence of these animals. Goat diet information is valuable in determining which species may be most susceptible to the action of these herbivores. This information can then be used in the development of management plans for local species or justify the eradication or more intensive control of the goats. We present data on the diet of feral goats from Mona Island, a dry forest reserve located between the islands of Hispaniola and Puerto Rico. Diet information was collected from 87 goat rumens collected by local hunters during January–April, 2003. The goats ate at least 86 plant species, 12 of which are currently under some protection status either by the Puerto Rico or the US Federal Governments. Harrisia portoriscensis (Cactaceae), P caulerpoides (Portulaccaceae), P monensis (Orchidaceae) and Z. taylori (Rhamnaceae), are critical species that were very frequent in goat diets and thus may need special conservation attention.