A damage in a structure alters its dynamic characteristics. The change is characterized by changes in the modal parameters, i.e., modal frequencies, modal damping values and mode shapes associated with each modal frequency. Changes also occur in some of the structural parameters; namely, the mass, damping, stiffness and flexibility matrices of the structure. In this paper, evaluation of changes in the flexibility matrix of a structure is presented as a candidate method not only for identifying the presence of the damage but also locating the damage. It is shown that the flexibility matrix can be easily and accurately estimated from a few of the lower frequency modes of vibration of the structure, which can be easily measured. First, with simple analytical beam models, the effect of presence of damage in a structure on its flexibility is studied. By using these analytical models, the effectiveness of using changes in the flexibility matrix in detecting and locating damages is demonstrated. The procedure is then tested with experimental data collected on a wide-flange steel beam.