The elastic scattering cross sections, σ (E,θ), for the systems He+Ta and He+W have been measured at θlab=165° and Elab=76.1 keV to 3.988 MeV using targets with a thickness of a few atomic layers. The results are smaller than the results given by the Rutherford scattering law, σR(E,θ), due to the effects of electron screening and can be described by σ(E,θ)/σR(E,θ)=(1+Ue/E)−1, where Ue is an atomic screening potential energy. The deduced average value, Ue=28 ± 3 keV, is consistent with the Moliere- and Lenz-Jensen-models as well as electron binding energies.