Platinum thin films with thickness in the range of 0.4-12 nm were formed by filtered vacuum arc plasma deposition on a substrate with anisotropic roughness. The electrical resistivity was measured in directions parallel and perpendicular to the surface modulation as a function of film thickness, and the resistivity was found to be anisotropic with the degree of anisotropy increasing with decreasing film thickness. The very small thickness of the films calls for a quantum model for film resistivity, and it is shown that the measured resistivity can be interpreted as due to quantum electron scattering by the thin film anisotropic surface roughness. (c) 2007 American Vacuum Society.