Single hyperthermia session causes an appreciable decrease in adrenocorticocyte count in the adrenal cortex in mice on day 3 of postthermal restitution. Morphological changes in the adrenals under conditions of developing stress reaction manifested in increased structural and functional heterogeneity of adrenocorticocytes in all cortical layers, exhaustion of lipid incorporations in the zona fasciculata cells, pronounced shrinkage of zona reticularis, developing against the background of hemodynamic disorders. Recovery of the total count of adrenocorticocyte population was associated with the appearance of small accumulations of immature cells in the subcapsular area of zona glomerulosa. Despite the absence of pronounced changes in the architectonics of all adrenocortical zones during postthermal restitution, recovery of zona reticularis was incomplete, which manifested in its shrinkage and persistence of degenerative changes in adrenocorticocytes.