Summary.Phosphate esters are accumulated in the intact livers of rats and rabbits during assimilation of hexoses and glycerol, which latter was examined on rats only.During absorption of fructose the fructose ester accumulated showed qualities similar to those offructose‐1‐phosphoric acid; no fructose‐6‐phosphoric acid was accumulated. The amounts of fructosephosphoric acid accumulated in the liver and in the intestinal mucosa of the same rabbit seem to be equal with regard to quantity and synthetising intensity. The amounts of ester may be calculated at about 100 mgs of the ester per 100 g of liver tissue; this amount was rebuilt almost completely within 4 minutes as shown in an experiment with radioactive phosphorus.The phosphate esters accumulated in livers of rats during absorption of glucose and galactose are probably to some extent aldose‐esters i. e. glucose‐6‐phosphoric acid (and galactose‐6‐phosphoric acid?). Some of the esters accumulated during absorption of glucose and galactose in the livers of rats and rabbits were very sensitive to acid hydrolysis and relatively resistant to hydrolysis with alkali; the possibility exists that these esters are glucose‐1‐ and galactose‐1‐esters respectively.During absorption of glycerol an amount of glycerol representing about 100 mgs glycerol per 100 g liver tissue of rats was esterified; as phosphoglyceric acid and triosephosphoric acid could be excluded, the ester in believed to be (α‐ ?)‐glycerophosphoric acid.No accumulation of fructose‐1‐phosphoric acid was observed in the kidneys or muscular tissue of rabbits during assimilation of fructose, but the contents of fructose‐6‐ester of the preexisti