Fluorescein and its derivatives fluoresceinamine and diiodofluoresceiniodoacetamide have been studied by surface enhanced resonance Raman spectroscopy (SERRS). Adsorption of the dyes at the silver/electrolyte interface requires attractive interactions between polar side groups (such as NH2, OH and COOH) with the metal as a prerequisite for Raman enhancement and fluorescence quenching. It was possible to characterize two prototropic forms of fluorescein and fluoresceinamine by their SERR spectra. Only vibrations of the chromophoric part (xanthene) of the molecule contribute to the measured spectra. Substituents in the phenyl ring influence only the ability of adsorption and the structure of the adsorbed molecules.