Irradiation with doses of 0.02—0.3 kGy of γ-rays could cause varied damages to the cellular and subcellular structures of the shoot apical meristems in garic. The irradiated cells were elongated and cell walls were thickened. The highest radio-sensitivity was found in the- vacuoles which developed morphological abnormality before the end of dormany, while the nucleis and nucleoli, which remained intact even after the cell walls were broken, demonstrated the highest resistance to irradiation. The observed morphological damages were of higher magnitude in sprouting period than that in dormancy in which irradiation treatments were conducted, suggesting that metabolism plays an important role in the development of initial irradiation lesions into structural damages in the cells.