DESPITE MANY valuable aids in the diagnosis of acute pancreatitis, in certain instances differentiation among severe diseases of the upper abdomen is difficult and important. The typical clinical picture of sudden pain, vomiting, and distention and guarding of the abdomen always leads to a consideration of pancreatitis, but other catastrophic disorders may be similarly manifested. In one case operation is mandatory and in the other contraindicated. The significant abnormal laboratory test results, increased serum amylase and lipase, hyperglycemia, glycosuria, increased urinary diastase, and hypocalcemia may not be helpful since they are present in other disorders or may be equivocal in pancreatitis. A study is reported which indicates that Sulkowitch's test, a simple bedside determination of urinary calcium, may be a valuable aid in the early diagnosis of pancreatitis. The role of the calcium ion in this disease was first pointed out in 1882 by Balser,1who applied the term