[en] A variational principle is used to calculate, in a relatively simple manner, the frequencies of quadrupole oscillation of relativistic neutron star models for a variety of equations of state and central densities. Typical periods and damping times are on the order of milliseconds and seconds, respectively, in agreement with earlier estimates obtained by Thorne in a different manner. For spheres of incompressible fluids, the analyses indicate that the fundamental quadrupole mode becomes unstable as 2M/R attains its limiting value of 8/9