The dynamic behaviour of structures, in particular, that of a rotor, containing cracks is a subject of considerable current interest. Several researchers have developed models of cracked rotor systems considering mainly a single transverse surface crack. In the present study Finite Element (FEM) analysis of a rotor system for flexural vibrations has been considered by including two transverse open cracks The eigenvalue analysis and stability study of a rotor system including a shaft with two open cracks have been carried out and the influence of one crack over the other for eigenfrequencies, mode shapes and for threshold speed limits has been observed. © 1999 Academic Press.