The structure of rat lymph nodes regional to the purulent wound under the conditions of interleukin (IL-2) treatment was investigated by the methods of light microscopy. In the lymph nodes from intact animals, the cortical plateau was found to become diminished with the simultaneous paracortical zone expansion. In the regional lymph nodes from rats with an untreated purulent wound, the relative dimensions of cortical plateau were decreased because of expansion of the medullary structures. Lymphoid parenchyma and the sinuses of lymph nodes contained erythrocytes, the numbers of immuno- and plasmoblasts, macrophages and neutrophilic granulocytes were increased. IL-2 treatment in animals with a purulent inflammatory reaction secured the greater integrity of structure of these organs and of cytoarchitecture of their various zones. However, the administration of this cytokine resulted in increased vascular permeability and enhanced the probability of allergic reaction development, which requires the development and application of prophylactic measures of the specified side effects and complications.