question: BACKGROUND: Lymphoma cells are highly radiosensitive and consequently, radiation therapy is a rational addition to systemic therapy in the treatment of leukemia. Especially as a conditioning regimen before allogeneic stem cell transplantation, radiation therapy, in the form of total body irradiation, is an established concept. OBJECTIVES: The present work provides an overview on the execution and side effects of radiation treatment in leukemia. Especially (long-term) side effects after total body irradiation are presented. MATERIALS AND METHODS: A selective search in the database PubMed on radiation treatment of leukemia and on total body irradiation has been carried out, focusing on toxicities as well as technical and conceptional innovations. RESULTS: Total body irradiation is a successful conditioning therapy before allogeneic stem cell transplantation and is accompanied by a diverse, but manageable, toxicity spectrum with endocrinological, cardiopulmonary, ophthalmological, nephrological and neurological long-term side effects as well as secondary neoplasia. In addition, low-dose radiotherapy may be utilized to treat myeloid sarcoma (chloroma). CONCLUSIONS: The variety of side effects after total body irradiation requires an interdisciplinary and long-term aftercare provided by radiation oncologists and medical oncologists/the transplantation team. Technical evolutions may result in a more selective targeting of the bone marrow and lymphatic organs. At the moment, these techniques are not established in clinical routine but are being evaluated in clinical trials.