Objective Sex difference of the length ratios of metacarpals and metatarsals in Macaca mulatta from the Taihang mountains was studied in our laboratory. Methods The lengths of 27 metacarpals (10 males, 17 females) and 30 metatarsals(12 males, 18 females) were measured from the skeletons of 30 adult EM>Macaca mulatta/EM>. Length ratios were constructed for all possible pairings of the five bones in each individual hand and foot. EM>One-Way ANOVA/EM>  adopting SPSS13.0 for windows was used to study the sex differences of length ratios of metacarpals and metatarsals. Results For EM>Macaca mulatta/EM>, several of these lengths ratios exhibited substantial differences between the sexes. The metacarpal(Mc) length ratios showing the largest sex differences were 2Mc∶5Mc and 4Mc∶5Mc in both hands (EM>P/EM><0.01), and the metatarsal(Mt) length ratios showing the largest sex difference was 1Mt:3Mt in both feet (EM>P/EM><0.05). Conclusion The sex differences of metacarpals and metatarsals remained when specimens of similar size were compared. It showed that body size was not the basis for these sex differences. Various facts suggested that the sex difference of length ratios in primate metapodials was associated with sex hormones exposure, possibly