Stationary direct perturbation theory is used to calculate a scalar relativistic correction to the species in the G3/99 test set. We observe that the relativistic energy almost always reduces atomization energies, electron affinities, and ionization potentials. Exceptions occur when s orbitals play a predominant role in the energy differences between reactants and products. The scalar relativistic energy, when added to G3 theory and the empirical parameters are reoptimized, gives slightly worse agreement with experiment.