[en] Purpose: The goal of this course is to develop a thorough understanding of the rationale for and the design of total body irradiation (TBI) as a component of the conditioning regimen for bone marrow transplantation. Methods and Materials: There will be a review of the basic radiobiological principles relevant to TBI. Included will be a discussion of relevant laboratory data useful in optimizing TBI delivery. Techniques used at various centers will be described with thorough discussion of partial organ shielding as well as boosting 'selective organs'. A review of clinical work currently available will be performed. Addressing the role of TBI containing conditioning regimens in preparation for bone marrow transplantation compared to chemo only regimens will also be done. Results: After the discussion performed above the attendee should be able to understand the appropriate method for delivery of TBI in different settings. The discussion will be very clinically oriented so as to allow for complete understanding of appropriate methods of delivery of TBI as is currently available. Conclusion: TBI remains an important component of cyto reductive regimens for marrow transplantation in patients with leukemias, aggressive lymphomas, as well as some benign conditions. Appropriate understanding of dose rate, total dose, and fractionation as well as dose to individual organs is critical in successful utilization of this form of external beam irradiation