Stopping powers are one of the major factors that affect the accuracy of Rutherford backscattering analysis methods. Their role becomes most important when thicknesses greater than 0.5 mg/cm 2 are probed with hydrogen beams of 1.0 MeV or less. The analysis of data taken under these conditions require energy loss values near the peak of the stopping power curve where the uncertainties can reach 15% or more. The RBS simulation code PROFILE is used to analyze samples containing Cu, Ni and Al with several different sets of stopping powers. The results indicate that a given uncertainty in the stopping power may lead to equivalent uncertainties in elemental concentrations and thicknesses of coatings.