Abstract: The presence of closely spaced modes of vibration in current modern engineering structures seems to be unavoidable and failure in identifying them may lead to inability to accurately derive models for the structures. In this study, a technique for experimental investigation of closely spaced modes of a structure is presented. Free boundary conditions were used in experimental work and simulations. For the validation purposes, the natural frequencies and mode shapes of the structure were measured using three different points and the measured results were compared with those predicted from the finite element method. In this study, the proposed technique was successfully used for accurately identifying the closely spaced modes of the structure.