This paper deals with the investigation of the sensitivity of the eigenvalues of a special mechanical system. It consists of a clamped-free Bernoulli-Euler beam carrying a tip mass. The vibrations of the beam are damped by a viscous damper which is attached to it within the span. The main concern lies in the determination of the sensitivities with respect to the changes in the magnitude of the damping constant, tip mass ratio and location of the damper attachment point, around their nominal values. (C) 1998 Academic Press.