The effect of gamma-irradiation on the structure and magnetic properties of ferrite samples with chemical formula Mg (x) Cu0.5-x Zn0.5Fe2O4 (where x = 0.0, 0.2, and 0.4) prepared by conventional ceramic method has been studied. X-ray diffraction patterns (XRDPs) indicated the presence of a single spinel phase for all the investigated samples. The initial permeability and magnetization were measured, before and after irradiation on toroidal samples used as transformer cores. The initial permeability mu(i) was measured as a function of temperature at constant frequency of 10 kHz and Curie temperatures (T (C)) were determined. It was found that, due to irradiation, both of lattice parameter and porosity were increased. On the other hand, the values of magnetization and initial permeability were decreased as a result of irradiation. In addition, there was a decrease in the crystallite size, homogeneity, and the values of Curie temperature with significant decrease in the values of mu(i) and T (C) for the sample with x = 0.0. The results are discussed in the light of gamma-rays interaction with ferrite lattice.