Implantation of polycrystalline silicon films (poly-Si) with H+, He+, N+, and Ar+ ions at doses between 1013 and 2 × 1017 ions cm−2 are studied. The number of paramagnetic vacancy-type defects (VV-centres) ΔNvv are measured by EPR technique at 77 K. Also the structure of poly-Si and effective grain size are controlled by electron diffraction. Implantation of poly-Si with H+, H+, and H ions is found to lead to the appearance of VV-centres in contrast to the data on Si single crystals. There are two stages in the dose dependence of ΔNvv. When ΔNvv is saturated at high doses the poly-Si layers are not completely amorphized by H+ and H2+ irradiation as distinguished from the samples, implanted with N+ and Ar+ ions, where the amorphization dose Da is less than that of Si single crystals by a factor of 100. Da is found to increase for the implanted samples of poly-Si annealed before. The discussion of the results obtained is based on the assumption of the important role of intrinsic stresses in the accumulation of defects in poly-Si up to amorphization. [Russian Text Ignored].