The present paper deals with study on protective measures against irradiation malaise after a large dose and short term of irradiation. More than a thousand patients undertaken esophagoectomy have been experienced in our clinic and most of them have almost been irradiated before the operation to secure and promote the curability of the patients. However, preoperative irradiation has been followed by various kinds of complications; lassitude, anorexia, headache, leucopenia and liver damage.With this in mind, autologous bone marrow transplantation has been studied experimentally in our clinic.The method is as follows, about 17.1×106-22.9×106 of myelocytes aspirated from the bone marrow of the rabbits and kept at 4°C, transfused into them through the right ear vein which 1500 r of 60Co had been irradiated before.Then, good results have been obtained: First, survival time has been prolonged. Secondly, tendency of body weight and white cell count has been improved. Thirdly, histologic aspects of liver, adrenal glands and especially bone marrow damaged with irradiation have been alive and parenchymatous.