An intestinal amylase has been separated and identified in the rat. Intestinal amylase is located on the brush border and is identical with one or both of the heat-stable maltases. Intestinal amylase is particularly active against oligosaccharides, slightly active against soluble starch, inactive against oligosaccharides, slightly active against soluble starch, and inactive against insoluble starch. This amylase may be important in the digestion of small oligosaccharides derived from starch. Pancreatic contamination of intestinal mucosa was extremely difficult to eliminate. Biliary or pancreatic diversion removed most of the contamination; washing procedures alone were not adequate. Pancreatic amylase was adherent to intestinal mucosa in vitro. Thus, when studying intestinal enzymes, pancreatic contamination must be carefully excluded as a source of enzymatic activity.