[en] Bone marrow of locally irradiated shinbone (2000 R) has always been resorpted when transplanted under renal capsule of mice of the same line 0 to 4 months after the treatment. At the same time bone marrow of unirradiated legs of the same donors have always possessed osteogenic potentials. It is concluded that the stroma of irradiated limbs is defective and can not be regenerated by repopulation of stromal elements from unirradiated reqions. The same conclusion has been reached after experiments with repeated irradiation of mice and shielding of one and the same limb. According to the heterotopic transplantation data, the stromal elements, unlike hemopoietic ones, are unable to be repopulated