The preventive effects of contrast media containing ulinastatin (UST) and/or prednisolone (PDN) on potential complications associated with endoscopic retrograde cholangiopancreatography (ERCP) were studied in 111 patients. The incidence of abdominal pain and the elevation in the serum amylase level after ERCP were lower in the UST group than in the control group and abdominal pain and the elevated serum amylase level were almost completely suppressed in the PDN and UST/PDN groups. Based on these findings, a comparative study was conducted to evaluate the effectiveness of a combination of UST and PDN, given via the pancreatic duct, in alleviating pain symptoms in 57 patients with chronic pancreatitis and abdominal pain. The post-ERCP serum amylase level in some patients in the PDN and UST/PDN groups was lower than the pretreatment value. After ERCP, the abdominal pain that had been experienced before ERCP was relieved, and the value of the bentiromide-paraaminobenzoic acid (BT-PABA) test had improved. These results suggest that the use of contrast media containing PDN or UST/PDN in patients with chronic pancreatitis is extremely effective not only for preventing potential complications related to ERCP but also as a new diagnostic treatment method.