The following perfusion media for dissolving bile duct calculi were infused via a cutaneobiliary tube into the biliary tract of 12 mongrel dogs: 4.3% cholate solution, 0.34% chenodeoxycholate solution, Capmul, GMOC (special formulation of Capmul), BA-EDTA and 0.9% saline. Infusion lasted 50 h. Postmortem examination revealed hemorrhagic, partly phlegmonous cholangitis, acute duodenitis, necrosis and abscesses in the liver. The lesions were most pronounced after the cholate solution and with Capmul and GMOC, but were only detected to a slight extent after BA-EDTA and the chenodeoxycholate solution. 0.9% saline had no side effects. The investigations could demonstrate that it is the very irrigation media that today are recommended for treatment of bile duct stones in patients, that cause considerable morphologic side effects. The alternating administration of an EDTA solution with a Capmul preparation may diminish local toxicity of the latter.