The limb musculature of the tree shrews,Tupaia glis, Tupaia nicobarica, Lyonogale (Tupaia) tana, andUrogale everetti, is described and compared with published accounts. Although these species show preferences for different forest levels, i.e., arboreal (T. nicobarica), semiarboreal (T. glis), and terrestrial (L. tana, U. everetti) niches, their musculoskeletal contrasts present no consistent patterns attributable to locomotor adaptations. However, a re-examination of the myological evidence bearing on the much discussed question of the relationship of tree shrews to primates suggests that those features shared by these forms are retentions from their basal mammalian heritage, and supports the view that tree shrews possess a primitive rather than a progressive insectivoran limb morphology.