Proximate analysis of twelve types of fruits commonly consumed by long-tailed macaques (Arenga pinnata, Arena catechu, Terminalia catappa, Elaies guineensis, Lagerstroemia tomentosa, Mangifera indica, Cascabela thevetia, Muntingia calabura, Musa spp., Artocarpus heterophyllus, Ficus tinctonia ssp. gibbosa and Ficus microcarpa) was conducted with the specific objective to determine the nutritional composition of the foods of long-tailed macaques. The crude protein content was analyzed by using Kjedahl method, crude fibre was analyzed by using FibreBag System by Gerhadrt, crude fat was analyzed by using Soxtec Extraction method and mineral contents was determined through the percentage of ash. The result shows the following order of nutrients: fibre, protein, fat, ash and moisture content. Based on the results of the chemical analysis, the highest percentage of fibre content (52.73%), protein (9.86%), fat (77.25%), ash (8.53%) and moisture content (86.55%) are found in Areca catechu, Arenga pinnata, Elaies guineensis and Cascabela thevetia. The nutrient compositions from these twelve types of fruits are found to be different from each other. The results show that fibre is the highest among the four types of nutrients that have been studied and it has been supporting the initial hypothesis of this study. These results also prove that long-tailed macaques prefer fruits compare to the other part of plants.