Fecal chymotrypsin (FCT) has been measured by a new photometric method (Monotest Chymotrypsin; Boehringer, Mannheim) in 78 patients: 44 with chronic pancreatitis and 34 not affected by any pancreatic disease. The results were compared with those from other tests of pancreatic secretory (secretin-cerulein test) and digestive [serum and urinary p-aminobenzoic acid (PABA) and pancreolauryl] capacity. When FCT values were severely reduced (below 6.7 U/g), from 90 to 100% of the patients also presented abnormal pancreatic secretory and digestive capacity. On the other hand, 87% of the patients with normal FCT (above 20 U/g) presented normal secretory and digestive capacity. Patients with intermediate FCT values (between 6.7 and 20 U/g) showed normal or abnormal pancreatic secretory and digestive capacity with the same probability. Therefore, FCT, carried out as a first test, seems to identify subjects that need no further pancreatic function tests (normal and severely impaired FCT) and patients who need other more complex functional investigations (intermediate FCT values).