A number of laboratory tests (uniaxial, triaxial and hydrostatic) were conducted on a dry porous limestone. A conceptual model is proposed to correlate deformation and damage fields with the variation of ultrasonic velocities and quality factors. This correlation is presented in a stress deviator versus confining pressure diagram. In this way, the successive steps occurring in the damage process of this rock are well described. In particular, the quality factor of the S wave distinguishes clearly the onset of the initially stable cracking, while velocity of the S wave and strain measurements are sensitive to dilatancy which appears later in the damage process of the studied limestone.