Collared peccary (Tayassu tajacu) and wild pig (Sus scrofa) exist in sympatry in southern Texas. These species vary in the structure of the digestive system and in adult body size, which might influence digestive performance. Our objective was to assess differences in digestive system efficiency between these species, controlling for body size. Four peccaries and 4 young pigs of similar size were fed a standardized amount of a commercial feed (38% neutral detergent fiber, 12% crude protein) based on metabolic body weight (kg^0.75) for 8 days. Feed consumed and feces produced were measured during the last 5 days of the trial. No differences were found for digestive performance between the 2 species, although pigs excreted 95% of chromium-marked fiber sooner than peccaries. Although peccaries have a complex stomach in which fermentation occurs, they apparently do not gain a significant benefit in digestibility of dry matter, energy, or fiber relative to a hindgut fermenter of similar body size when eating similar amounts of food. Peccaries might, however, benefit from microbial products (e.g., vitamins and amino acids) that would not be readily available if fermentation occurred exclusively in the hindgut. Our results do not suggest that either species has a competitive advantage in dry matter digestion of plant material.