The experiments have been performed on 77 mature male rabbits. Light and electron microscopic, as well as immunofluorescent methods have demonstrated that a single local application of superhigh-frequent electromagnetic field of nonthermal intensity to the testes results in structural disturbance and in disorders of permeability of the hemato-testicular barrier, in ultrastructural changes of the tunica propria of the convoluted seminiferous tubules, and is accompanied with the development of auto-immune process in the testes; that causes certain distrophic changes in the spermatogenic epithelium and destruction of sex cells, predominantly those at the latest developmental stages. According to individual sensitivity, 3 groups of the animals have been revealed that variously respond to the damaging effect of the superhigh-frequency electromagnetic field. The damaging effect is produced by two immunologic mechanisms-humoral (antibodies) and cellular (sensitized lymphocytes).