Surface-enhanced Raman scattering (SERS) using pyridine as probe molecule was studied by modification of Ag-electrodes with deposition of Cu submonolayers. Already at a coverage of θ = 0.003 (SERS) active sites, so far associated with Cu atoms, become more stable and new bands typically for Cu-pyridine surface complexes begin to rise whereas those for Ag-pyridine drop. Since electromagnetic enhancement at roughened electrodes is estimated to be less than 1000, these effects evidence the dominant role of local enhancement processes in SERS