Hypotonic cholangiography was performed with i.v. glucagon in 12 patients who demonstrated complete nonspecific obstruction of the distal common bile duct during postoperative T-tube or transhepatic cholangiography. In 8 cases (67%), a diagnostic result was obtained. Abolition of smooth-muscle spasm at the choledochal sphincter by glucagon-induced hypotonia appears to be a useful adjunct to roentgenography of the bile ducts.