The relationship between talar size and body mass in extant primates is examined to provide the regression equations for estimating the body mass of extinct primate species based on the talar size. The results indicate that, among the linear talar dimensions, the whole talar size and the tibial trochlear size are good body mass estimators for primates. As an example, the regression equations presented here were applied to the body mass estimates of the fossil tali (NMMP-39 and NMMP-82) of the amphipithecid primates from the middle Eocene Pondaung Formation of Myanmar. Based on the estimated body masses determined by this study, NMMP-39 (estimated body mass: ca. 2.7kg) should likely be assigned to Ganlea megacanina or Myanmarpithecus yarshensis, while NMMP-82 (estimated body mass: ca. 4.9kg) should likely be assigned to Amphipithecus' mogaungensis or Pondaungia cotteri.