Records of 346 patients were studied to determine the reliability and diagnostic value of pancreatic scanning. In 157 the pancreatic diagnosis was established subsequent to scanning. The scan was abnormal in 28 of 34 patients (82%) with pancreatic neoplasm, and in 21 of 26 patients (81%) with chronic pancreatitis. Of 71 with normal scans, 56 (79%) had a normal pancreas, and 15 had pancreatic disease (a false negative rate of 21%). Of the 86 with abnormal scans, the pancreas was diseased in 56 (65%), and of the others, 14 had extrapancreatic conditions known to be associated with a high incidence of scan abnormalities. In obstructive jaundice all 21 patients with pancreatic carcinoma had abnormal scans (and the scan accurately diagnosed all four cases of bile duct carcinoma). A normal scan reliably indicated that the cause of jaundice was outside the pancreas. In chronic abdominal pain an abnormal scan was unreliable, but a normal scan excluded pancreatic disease with reasonable accuracy.