We report on four patients of our own and another thirty-six from the literature, who developed almost identical and unusual clinical syndromes after surgical treatment of hydatid disease of the liver, with the aim of showing the extremely serious nature of the problem that can ensue. An association of four factors seems to be necessary to promote caustic sclerosing cholangitis: a) injection of a scolicidal agent (formalin, hypertonic saline, ethanol, silver nitrate or iodine solution) into the cyst cavity; b) a communication between the cyst and the biliary tree; c) a condition that prolongs the exposure of the biliary tree to the scolicidal; and d) a particular sensitivity to the scolicidal agent. While this last condition cannot be anticipated, we may justifiably conclude that surgeons should not inject a scolicidal solution into the hydatid cyst, but prevent intra-abdominal diffusion of the parasite by using hydrogen peroxide, gauze pads moistened by a scolicidal solution or by preoperative chemotherapy with albendazole. Caustic sclerosing cholangitis has an earlier onset of symptoms and a more rapidly progressive nature than primary sclerosing cholangitis. In foresight, serum alkaline phosphatase should be monitored and, when raised, a retrograde endoscopic cholangiogram and/or a liver biopsy should be performed. Digestive shunt surgery should be avoided and the possibility of liver transplantation has to be periodically evaluated.