Jejunal perfusion studies were performed to assess water, electrolyte, d-xylose, and d-glucose transport in 16 patients with chronic calcific pancreatitis (eight with and eight without steatorrhoea) and in 10 control subjects. The patients with steatorrhoea demonstrated significantly less xylose, water, and electrolyte absorption than patients without steatorrhoea and control subjects, when an isosmotic slaine-xylose solution was perfused. On the other hand, when an isosmotic saline-glucose solution was perfused, the patients with steatorrhoea absorbed significantly more glucose, water, and electrolytes than control subjects. Significant correlation was demonstrated between the absorption of xylose as measured by the segmental perfusion technique and the peak serum xylose level during perfusion as well as the five-hour urinary xylose excretion after a 25 g oral dose of xylose. The xylose absorption measured by small bowel perfusion also correlated significantly with pancreatic juice amylase and trypsin concentrations obtained during a standard pancreatic function test.