In a new attempt at species identification, the total composition and positional distribution of fatty acid in triacylglyceride (TG) of adipose and bone tissues were analyzed in human, bovine, pig, dog, cat and chicken tissues. Although the total fatty acid compositions of bovine and pig tissues were significantly different from those of human (different in more than half the fatty acids tested), dog, cat and chicken tissues showed a comparatively similar composition to human fatty acids composed of TG in both tissues. The TG in these tissues was also subjected to stereospecific analysis using pancreatic lipase, that is, the fatty acid distribution in positions 1,3 (not distinguished between 1 and 3) and 2 of the TG were determined. The distribution of fatty acids among the positions 1,3 and 2 in the TG of animal adipose and bone tissues was non-random. The distribution between position 2 and positions 1,3 seems to be governed by chain length and unsaturation in each animal. The shorter and more unsaturated fatty acids showed a greater tendency to occupy position 2 of TG. Although this rule appeared in all animals except the pig, the distribution of each fatty acid into position 2 was species-specific. The positional distribution of fatty acid in TG was identical among the same species and in different regions of the same body. Thus, even when species identification is difficult using the pattern of total fatty acid composition, the analysis of the positional distribution of fatty acid makes it possible to determine the species. From the present results, the evaluation of positional distribution of fatty acid in the TG is a useful tool for the identification of human tissues.