Objective To investigate the size variation in the first metatarsal of extant primates.    Methods In this study, we analyzed 135 first metatarsal specimens across 12 primate genera, quantifying eight linear measurements, articular surface areas, mid-shaft cross-sectional area, total surface area, volume, and derived indices. Multivariate patterns were assessed through mean-based correspondence analysis and principal component analysis (PCA).    Results Eulemur, Otolemur, Cebus, and Perodicticus exhibited a relatively high metatarsal surface-area-to-volume ratio. Perodicticus additionally showed a low articular facet index. Propithecus, Colobus, and Macaca displayed lower values for metatarsal shaft robusticity, the ratio of shaft cross-sectional area to base articular surface area, and the proximal articular facet index. Nasalis possessed a relatively high articular facet index. Pongo, Pan, Gorilla, and Homo sapiens were characterized by higher metatarsal shaft robusticity and a lower metatarsal surface-area-to-volume ratio. Principal component analysis revealed that the 12 extant primate genera could be broadly divided into two groups. Group 1 comprised Pongo, Pan, Gorilla and H. sapiens, although H. sapiens formed a distinct cluster relative to the extant great apes. Group 2 included Eulemur, Otolemur, Perodicticus, Propithecus, Cebus, Colobus, Macaca and Nasalis .   Conclusion The relative sizedistribution of the first metatarsal provides some reference value for classifying extant primates. However, it demonstrates no clear correlations with specific locomotor patterns or foot grasping ability.