The penetration depth into a medium of sagittally polarized Rayleigh waves propagating on a planar stress-free surface of an isotropic medium, has been considered. Using values of the ratio cR/ct(where cRdenotes the velocity of the Rayleigh wave, and ct, the velocity of the transverse sound wave) calculated from the dispersion relation for the Rayleigh surface wave, the penetration depths (kβL)-1and (kβt)-1defined by Maradudin, have been calculated as functions of the ratio CR/CL, (where cLdenotes the speed of the longitudinal acoustic wave), the ratio cR/ctand also of the Poisson's ratio σ. The amplitudes of the components U1and U3of the displacement field for sagittally polarized Rayleigh waves have been calculated as function of the distance x3from the surface, for various values of the Poisson's ratio σ.