Pancreatic tissue fluid pressure was measured in 10 patients undergoing drainage operations for painful chronic pancreatitis. The pressure was measured by the needle technique in the three anatomic regions of the pancreas before and at different stages of the drainage procedure, and the results were compared with preoperative endoscopic retrograde cholangiopancreatography (ERCP) morphology. The preoperatively elevated pressure decreased in all patients but one, to normal or slightly elevated values. The median pressure decrease was 50% (range, 0-90%; p = 0.01). The drainage anastomosis (a pancreaticogastrostomy) was made in the body of the pancreas, but the pressure decrease in this region was not significantly different from that in the head and tail. The pressure decrease was independent of findings during ERCP (stone, total duct obstruction, or major ductal stenosis). In conclusion, the results showed a decrease in pancreatic tissue fluid pressure during drainage operations for pain in chronic pancreatitis. Regional pressure decrease were apparently unrelated to ERCP findings.