OBJECTIVE: To formulate a more comprehensive and generalizable model than is currently available that fully accounts for costs associated with blood transfusions. METHODS: A consensus panel of experts in transfusion medicine was organized by the Society for the Advancement of Blood Management (SABM), representing clinical, blood banking, and academic interests. An iterative process was used to refine data from worksheets that had been distributed, collected, and summarized prior to the conference. RESULTS: A detailed process-flow model was constructed, encompassing both direct and indirect cost elements. Major steps and critical interdependencies were identified, including donor recruitment/qualification, blood collection, blood component processing, laboratory testing, unit tracking and labeling, blood destruction, donor notification and tracking, blood center/collection facility inventory, storage, and transport, transfusion service inventory and storage, pretransfusion preparation, transfusion administration and follow-up, and long-term outcomes tracking. Within these major steps, 248 cost elements were itemized. The relative importance and degree of difficulty associated with collecting cost data for each element were rated. Panelists rated personnel, screening for infectious agents, information systems, laboratory evaluations, transfusion reaction management, and equipment as the most important elements to capture. Limitations in current process-flow models were recognized, with deficiencies in accounting for both direct and indirect costs. Work is in progress to convert the present model into one that employs activity-based costing (ABC) which will correct the underestimates of blood costs provided in existing literature. CONCLUSIONS: Accounting for the cost of blood is an enormously complex undertaking and a standard, widely applicable methodology is needed. As presented, this process-flow diagram and comprehensive set of cost elements should be of interest to providers, payers, and society. When completed, the ABC model will be a more precise means to compare the cost of blood to that of transfusion alternatives or for evaluating safety-related improvements to blood administration technology.