Electrogenerated luminescence of lanthanides is reviewed with emphasis on the electrochemiluminescence (ECL) of lanthanide chelates. Main application area of lanthanide chelates in this field is their use as electrochemiluminescent labels in bioaffinity assays such as in immunoassays or DNA probe assays. With lanthanide chelates as labels, hot electron-induced ECL at thin insulating film-coated cathodes outperforms ECL based on traditional electrochemistry at active metal electrodes. ECL excitation of lanthanide(III) chelates occurs normally by ligand-sensitized mechanisms wherein the ligand is first excited by redox reactions followed by energy transfer from ligand to the central ion, which finally emits by f–f transitions. Luminescent lanthanide ions can be excited at oxide-coated metal electrodes when these ions act as luminescence centers in the oxide film and/or at the oxide/electrolyte interface or as solvated in the close vicinity of the electrode surface. These ions typically show high field-induced solid-state electroluminescence when embedded inside of the oxide films and ECL at the surface of the electrode or in solution close to the electrode surface. These lanthanide-doped oxide films can be fabricated either by anodization of certain lanthanide-doped valve metals or from pure valve metals by anodization in lanthanide ion-containing anodization bath preferably with AC voltages. Some lanthanide ions can be electrically excited also in strongly acidic sulfuric acid solutions at platinum electrodes with mechanisms not known with certainty.