Experiments on white rats showed that electromagnetic radiation (24 MHz, 400 W/m and 20 W/m) caused leucopenia, reduction of E and EAC rosette formation of lymphocytes, functional activity of neutrophils within 2 months of radiation. No immunosuppressive effect was seen with 24 MHz, 100 W/m radiation, while 400 W/m inhibited E-rosetteformation in the presence of tissue antigens.