The immunobiological effect of electromagnetic microwaves applied to parietotemporal area was studied. It was shown that the exposure of parietotemporal area to microwaves produced an immunodepressive effect manifested in the decreased number of natural (background) antibody-forming cells. The exposure of parietotemporal area to microwaves was accompanied by glucocorticoid function stimulation in the adrenal cortex and thyroid function depression.