BACKGROUND. Acalculous cholecystitis (ACC) is an uncommon disorder of the biliary tract, accounting for approximately 6% of acute cholecystitis cases. In this study, cholecystitis was seen in 8 of 770 bone marrow transplant recipients, with ACC occurring in five (63%). METHODS. Records of 592 allogenic and 150 autologous BMT patients were reviewed for risk factors associated with ACC. RESULTS. Only the number of blood transfusions administered and the use of total parenteral nutrition were associated with ACC development. ACC occurred in 4 of 42 (9%) allogeneic recipients who required exchange transfusion for ABO incompatibility. ACC developed in one autogolous recipient alongside venoocclusive disease of the liver. There was no association between ACC development and preparative regimen, cyclosporine usage, graft versus host disease, or cytomegalovirus infection. CONCLUSIONS. ACC occurs more frequently in patients after ABO incompatible BMT requiring exchange transfusion than in other transplant recipients.