Using the laser-based technique of cavity ring-down spectroscopy extinction measurements have been performed in various gases straightforwardly resulting in cross sections for Rayleigh scattering. For Ar and N2 measurements are performed in the range 470 490 nm, while for CO2 cross sections are determined in the wider range 470 570 nm. In addition to these gases also for N2O, CH4, CO, and SF6 the scattering cross section is determined at 532 nm, a wavelength of importance for LIDAR applications and combustion laser diagnostics. In O2 the cross section at 532 nm is found to depend on pressure due to collision-induced light absorption. The obtained cross sections validate the cross sections for Rayleigh scattering as derived from refractive indices and depolarization ratios through Rayleigh's theory at the few %-level, although somewhat larger discrepancies are found for CO, N2O and CH4.