High-dose chemotherapy and total body irradiation with either allogeneic or autologous bone-marrow rescue has been used successfully in the treatment of various hematologic malignancies. Total body irradiation, despite its acute and late side effects, combined with cyclophosphamide remains one of the best conditioning regimens before bone marrow transplantation. Interstitial pneumonitis and veno-occlusive disease are major and lethal complications following bone marrow transplantation. In this article, morbidity after total body irradiation will be discussed.