The purpose of this paper is to discuss some of the laboratory procedures which may be helpful in the diagnosis of pancreatitis. They include the determination of the degree of enzyme activity in blood serum, duodenal juice, urine, and peritoneal fluid; the microscopic examination and chemical analysis of stools for evidence of impaired fat and protein digestion, and the glucose-tolerance test. In addition, reference is made to other laboratory tests which may reveal abnormalities in pancreatitis, such as the serum calcium concentration, the differential white blood cell count, the various liver tests, and the starch-tolerance test. A. ENZYMES IN BLOOD Procedures are available for determining the amylase and lipase activity of serum; however, no direct method of estimating trypsin is as yet available. The plasma antithrombin titer, which Innerfield and co-workers 1 believe reflects tryptic activity, is being evaluated in pancreatic as well as other diseases. 1. Serum Amylase. —Of