Enteric-coated trypsin and chymotrypsin were given orally to 12 fasted human subjects in a dose of 200 mg and 100 mg respectively. Estimation of trypsin and chymotrypsin in blood and serum revealed no consistent change in activity over the succeeding 9 h with respect to the zero-time test value, or to the values for the corresponding time intervals on a separate occasion omitting oral enzymes. The trypsin-inhibitor activity of serum was likewise unaltered in 4 subjects in whom this determination was made. Trypsin and chymotrypsin, administered in a dose of 200 mg of each to four subjects by duodenal intubation also failed to alter the blood and serum levels of these enzymes. In addition to these results, further reasons are given for regarding intestinal absorption of pancreatic enzymes as currently unproven.