The acute vanishing bile duct syndrome can be defined as an irreversible, rejection-related condition that affects hepatic allografts within 100 days after orthotopic liver transplantation and whose presence requires retransplantation. We have observed the acute vanishing bile duct syndrome in 5 of 48 consecutive patients (approximately 10%) who underwent orthotopic liver transplantation. In 4 cases, the condition progressed relentlessly within approximately 7 to 11 weeks after orthotopic liver transplantation from mild rejection to severe rejection to acute vanishing bile duct syndrome. A fifth patient had severe rejection in the first week and required retransplantation after 17 days because of thrombotic venoocclusive disease complicating the acute vanishing bile duct syndrome. Clinically, signs of impending acute vanishing bile duct syndrome included abrupt onset of fever and jaundice and marked elevation of serum bilirubin and alkaline phosphatase levels which persisted despite antirejection treatment. Biopsy specimens revealed destructive cholangitis (rejection cholangitis), ductopenia, and, if retransplantation was delayed, presence of noninflammatory, “burnt-out” portal tracts without bile ducts. We recommend to base the diagnosis of acute vanishing bile duct syndrome on documentation of severe ductopenia in at least 20 portal tracts which may require several consecutive needle biopsies. Rejection arteriopathy which was found in 3 of our 5 cases might have been another important diagnostic clue but could not be recognized prior to retransplantation. The pathogenesis of acute vanishing bile duct syndrome is not clear; until the condition had manifested itself, we found no qualitative differences between acute reversible and irreversible rejection. After retransplantation, severe rejection has recurred in the four patients who could be evaluated in this regard; one of these patients already needed a second retransplantation for vanishing bile duct syndrome.