We report the investigations of the behavior of the europium impurity in PbTe(PbSe) and of the influence of infrared laser radiation corresponding to the transparency range of their compounds on the electrophysical properties and ESR in order to determine the charge state and the position of europium in the lattice. The PbTe(PbSe):Eu single crystals having the cubic NaCl structure were grown by directional crystallization from the melt. The impurity content in the melt was 0,02’0,2 mass %. The europium impurity was introduced into the melt as the EuS compound. The crystals had a p-type conductivity with a hole concentration P77 = (2’5)·10 18cm-3 The crystals were exposed to infrared laser light of photon energy lower than the band gap, ħω < Eg, where Eg is the band gap of PbTe(PbSe) and ħω = 0,118 eV. The power density of the laser light reaching a crystal was less than the threshold power density corresponding to damage (or melting) of a sample. The temperature of PbTe(PbSe):Eu during such exposure to laser radiation did not exceed 150°С. Heat treatment under similar conditions and at the same temperature produced no significant changes in electrical properties. During the initial stage of such laser irradiation (for a period tirr.< 3h) we found that the density of holes in PbTe(PbSe):Eu crystals decreased and an inversion of the type of conduction took place. The time needed to cause inversion was governed by the laser radiation power density. The carrier mobility then changed by one or two orders of magnitude, depending on the previous history of a sample. The observed changes could be due to dissociation (under the influence of laser radiation) of the complexes rich in the metal component and subsequent filling of the vacant sites in the metal sublattice of PbTe(PbSe). This process should be accompanied by an increase in the concentration of isolated europium ions at the metal sites of PbTe(PbSe), which in its turn should increase the ESR signal of the impurity. An investigation of ESR in PbTe(PbSe):Eu single crystals was made using a VARIAN E-12 spectrometer operating in the 3-cm wavelength range, the measurements were carried out at temperatures of 20 ’ 300 К. The ESR spectrum of original samples PbTe(PbSe):Eu revealed seven fine - structure lines of low intensity (corresponding to S = 7/2), and each of them consisted of weakly resolved hyperfine structure lines. The laser irradiation of PbTe(PbSe):Eu increased considerably the intensity of the hyperfine structure lines and improved their resolution. The hyperfine structure was best resolved in the case of the strongest (due to the -1/2 ↔ +1/2 ) central line in the spectrum. Away from the center of the spectrum, the intensity of the fine-structure lines fell and the hyperfine structure became less resolved. When a magnetic field with the orientation H || <100> (Θ = 0) was applied the resolution of the fine-structure lines was the highest along the field scale. The existence of seven fine-structure lines corresponding to S = 7/2, and the angular dependence of these lines, indicated that the Eu impurity occupied the site position in the Eu2+ state, and that it can also occupy interstices and form clusters. An investigation of the temperature dependence of the ESR lines intensities enabled us to establish the sequence of the energy levels and the signs of the spin Hamiltonian constants. A detailed analysis of the results obtained allowed us to interpret all the lines in a spectrum and to identify the ESR hyperfine structure lines due to 153Eu and 151Eu.