Abstract: The evidences for the existence of surface-enhanced Raman Scattering (SERS) active sites in electrochemical systems, both the experimental results and related discussion, have been briefly, reviewed. The irreversible decay (quenching effect) and restoration in SERS intensity of Ag/KCI/piperidine system has been studied by using negative potential pulse and using oxidation-reduction cycle (ORC) treatment applied to silver electrode, respectively, It is found that boehdegcee of both the irreversible intensity decay caused by the potential pulse and the intensity restoration caused by the ORC treatment are almost synchronous for all bands of SERS spectra. Besides, the data given by X-ray photo-electron spectra (XPS) shows that both chloride and piperidine molecules are present on surface of silver electrode which has been immersed in aqueous solution of KCl plus piperidine for several minutes. No detectable SERS signal has been found before ORC treatment. All these results can be interpreted in terms of the concept of surface complexes as SERS active sites existing on the surface of silver eletrode.