Features of the effect of bombardment by relatively slow ions (with energies up to 100 keV) on semiconducting materials are considered. Types of structure damage and methods and results of their investigation are described. Much attention is paid to the change of the electric properties of semiconductors following bombardment by ions, with an analysis of the advantages of ionic doping, a summary of the results of experiments on the electric conductivity of the irradiated layers and the changes occurring in it during the annealing process, and with data on the effect of ion bombardm'ent on the behavior of the non-equilibrium carriers (radiative conductivity, luminescence). The change of the optical properties of semiconductors and the influence of bombardment on the diffusion of the impurities and on the chemical activity of the materials is also considered.