Abstract Direct non-operative injection of radio-opaque material through a cannula introduced at the duodenal papilla by means of a fibre-optic duodenoscope achieved opacification of the bile ducts, the pancreatic duct or the entire biliary pancreatic ductal system in 392 (89 per cent) of 439 patients in whom it was attempted. The desired ducts were opacified in 75 per cent of cases; the bile ducts in 206 out of 278 and the pancreatic duct in 120 out of 161 cases. The anatomical conditions found were: long common biliary pancreatic channel, 30 per cent; short common biliary pancreatic channel, 28per cent; two orifices in the hepatopancreatic ampulla, 24 per cent; two orifices on the duodenal papilla, 18 per cent; two orifices on the duodenum, there being no papilla, less than I per cent. Morbidity resulting from the procedure consisted of infectious reactions in 20 out of 295 patients in whom the bile ducts were opacified and hyperamylasaemia and abdominal pain in 28 out of 300 patients in whom the pancreatic duct was opacified. The method is of value in diagnosing the cause of cholestatic jaundice. In non-jaundiced subjects it may complement or clarify inconclusive cholangiograms or cholecystograms obtained by other techniques. If it shows dilated bile ducts operation should not be delayed, otherwise there is a risk of cholangitis. Pancreatic carcinoma may be revealed by stenosis, partial or total, of the pancreatic duct or by filling defects in the pancreatic parenchyma. Both chronic pancreatitis and pancreatic carcinoma may cause partial stenosis of the pancreatic duct. A filiform appearance of the pancreatic duct suggests chronic pancreatitis.