Both agar and acrylamide gel were used for the separation of a-amylase isoenzymes of serum, urine, saliva, and solid tissues from human, rabbit, horse, cat, dog, and pig. A detailed study of total amylase activities and of tissue distributions was made: there was marked variation from tissue to tissue and from species to species. The problems of the tissue origin of serum and urinary amylases are not yet completely solved.