The conditions of the protein-synthesizing system in neurons of the hippocampus (areas CA1 and C A3) and of the cortex (sensomotor region) in rats subjected to y-irradiation at a dose of 8 Gy under hypothermia (16 - 18 degrees C) and hypoxia-hypercapnia were investigated by fluorescent and electron microscopy. Under hypothermia, the protein-synthesizing system was shown to be damaged to a lesser degree and to be restored faster in comparison with similar neurons in rats irradiated at room temperature. In rats irradiated under hypothermia, the rRNA biogenesis and the protein-synthesizing activity of polyribosomes were restored in two days. The protective influence of hypothermia did not spread to changes in membrane structures (endoplasmic reticulum and Golgy apparatus); i.e., a partial loss of integrity and possible transformation of their structure caused by the irradiation and the restoration of these structures occurred at a lower rate.