THERE have been several recent investigations of blood proteolytic enzymes in patients with pancreatic disease. Both amidase and esterase reactions have been studied by the hydrolysis of synthetic peptide substrates. Increased enzymatic activity has been observed in patients with pancreatitis and pancreatic carcinoma with the use of the arginyl substrates benzoyl-arginine amide (BAA),1 2 3 4 benzoyl-arginine ethyl ester (BAEE)5 and tosyl-arginine methyl ester (TAME).6 , 7 Unsuccessful attempts to reproduce these results have been reported with the same substrates.8 9 10 11 12 13 The diversity of clinical results and the unproved specificity of these blood enzyme reactions indicate a need for clarification of their reproducibility and significance. This . . .