In the present study, the modal parameters of cracked plain cement concrete beams have been studied theoretically. A crack in a beam element introduces considerable local flexibility, which has been expressed by local flexibility matrix, the dimension of which depends upon the numbers of degree of freedom considered. An approach based on linear fracture mechanics theory has been used to find flexibility matrix for the cracked element. The FEM program has been developed for eigen-value problems to determine the modal parameters of the cracked beams. Changes in natural frequencies and mode shapes between the damaged and intact beam have been observed. Numerical studies are performed by considering simply supported beam with single and multiple cracks at different locations with different crack depths.