The relation between pancreatic tissue fluid pressure measured by the needle method and pancreatic duct morphology was studied in 16 patients with chronic pancreatitis. After preoperative endoscopic retrograde pancreatography (ERP) the patients were submitted to a drainage operation. The predrainage pressures were higher in the tail of the pancreas (29 mm Hg; range, 16-37 mm Hg) than in the head (18 mm Hg; range, 2-30 mm Hg; p = 0.02). The regional pressure differences were significantly greater in four patients who had previously undergone pancreatic surgery than in the 12 patients without previous surgery. A stone, total obstruction, or major stenosis in the pancreatic duct at ERP was related to a downstream pressure gradient significantly higher than found in a non-obstructed pancreatic main duct, but the relation was not uniform. Generally, there was no significant relation between pancreatic duct diameter and pressure, but in each individual patient, the regional pressure tended to be highest in the region with the largest duct diameter. In conclusion, the study shows considerable regional pressure differences in chronic pancreatitis and indicates that the intraoperative pressure measurements give important information supplementary to ERP about the pathologic process in patients with chronic pancreatitis.