A comparative evaluation of ERCP and the bicarbonate output 30 min after stimulation of the pancreas with secretin and cholecystokinin-pancreozymin, was carried out in 124 patients, of whom 65 were affected by proven chronic pancreatitis (PCP), and 59 by only suspected chronic pancreatitis (SCP). In PCP patients the false negative results were 14.7% and 21.5%, respectively. In 5 of the PCP patients with false negatives on ERCP and functional test a normal result of both the procedures was found. ERCP and bicarbonate output were found to be abnormal in 12% and 40%, respectively of 59 patients with SCP. In 30 SCP subjects both procedures gave a normal result, and only in two cases were results abnormal. A correct classification of the SCP patients with pathological bicarbonate secretion and normal ERCP seems quite impossible. The diagnostic usefulness of ERCP results is preeminent but the of carrying out both types of investigation together may give complementary information in the evaluation of pancreatic disorders.