The current paper includes the analysis of influence of local soil conditions on the spectral content of seismic ground motion. This study was possible due to the existence of geotechnical information on dynamical properties of soft soil layers from boreholes drilled in the vicinity of seismic stations. For each soil column the dynamic amplification as function of magnitude of earthquake was calculated. The combined contribution of seismic source and site effect to the spectral content of ground motion is discussed. It should be emphasized the necessity of carrying more effective studies in this area, which should include the necessity of the laboratory measurements of the dynamic properties of the soil and acquisition of better data from the boreholes in the vicinity of each seismic station. These data will improve the accuracy of the seismic hazard analysis and will lead to better seismic macrozonation of the region.