Secretin (1 CU/Kg) plus Caerulein (100 ng/Kg) or Cholecystokinin (1 or 2 IvyU/Kg) were given by rapid intravenous injection (Schedule 1) or by continuous infusion (Schedule 2) to 63 control subjects (C) and 69 patients affected by chronic pancreatitis (CP). Duodenal juice was collected for two and four 30-minute periods in schedule 1 and schedule 2, respectively. Volume, bicarbonate, and enzyme content were measured. Secretin-Daerulein, by rapid intravenous injection, showed a strong overlapping between C and CP values and led to some side-effects. Secretin-Caerulein by continuous intravenous infusion gave almost identical results as the Secretin-Cholecystokinin.