In recent years microscopic study of wear patterns on molar teeth has provided useful inferences on the diet of fossil hominoids. This is the first attempt to reconstruct dietary information from the analysis of anterior (incisor) teeth. Central incisors of four sympatric primate species form Sumatra (Macaca fascicularis, Presbytis thomasi, Hylobates lar, and Pongo pygmaeus) will be examined by scanning electron microscopy. Features will be quantified using a semi-automated image analysis procedure, and species will be compared on the basis of revealed dental microwear patterns. These patterns will be use to generate predictions concerning degree of incisor use, items contracting these teeth, and type of ingestive behavior. Resulting predictions will be evaluated by observing the same four living primate species in their natural habitat at Ketambe, in northern Sumatra. The proposed research will (1) introduce a precise an rapid procedure for the quantification of dental microwear, (2) provide data on incisor microwear and tooth use among Sumatran primates, and (3) determine associations between incisor use and microwear so that the former may be predicted for the latter. Such associations will facilitate dietary inferences for fossil incisors.