The study of electrical conductivity, Raman and IR spectra, and microhardness of both polycrystalline and single crystalline forms of samples has proved that the kind of incorporation of tungsten into the YSZ lattice is a function of its concentration. However, the influence of tungsten impurity on the investigated physical properties of YSZ is rather weak. The electrical conductivity does not change markedly its character with an exception of an anomaly at 0.1-0.2 wt% WO3. The observed decrease of the intensities of the defect-induced Raman bands can be caused by the strong electronic influence of W6+ ions on their environment and by the decrease of the number of oxygen vacancies in the structure. The dependence of the microhardness on the temperature is stepwise. The inhomogeneities observed are connected with different impurity phases. The microhardness is independent of the presence of tungsten above 375 degrees C, which indicates the absence of tungsten containing impurity phases at these temperatures.