Dynamic characteristics of the structure represent its personal card. By monitoring them it is possible to get relevant information about the structural state and its degradation. The differences in measured dynamic characteristics at two stages in the life of structure reveal change in the stiffness/mass of the structure, location of the change and it is possible to conclude about the size of change in regard to the initial state. Outlined are two methodologies for structural damage identification by means of dynamical testing. They have been calibrated on the simple models and have proven its applicability to the real building structure for which only a limited amount of measured data is available. Methodology 1 requires knowledge of the measured dynamical characteristics of a structure at its initial state and after the damaging event. By means of the structural identification from the measured dynamical characteristics and comparing the change of relative shear stiffness between the neighboring stories the location and amount of structural change/damage is estimated. Methodology 2 is used when there are no data about the initial structural dynamic characteristics. A structural model with the use of finite element is made for the structure in its undamaged state. Measured dynamic properties such as frequencies and mode shapes of the structure in its damaged state are also needed. Using system identification techniques on both data sets and using the method of relative shear stiffness or the method of residual forces the location and amount of the structural damage could be estimated. It is applicable for the structures that could be described by the FEM.