The absorption, excitation, and fluorescence spectra of the diterpenoid alkaloids, lappaeonitine and N-deacetyllappaconitine, in acetonitrile were studied. On the basis of the coincidence of the spectra with the analogous spectra of model compounds, methyl esters of anthranilic and N-acetylanthranilic acids, the conclusion was drawn that the --OOC(Ph}NRH groups are fluorochromes in the alkaloids studied. The high quantum yield of fluorescence and the bathofluoric shift in the luminescence and absorption spectra of N-deacetyllappaconitine were explained by an increase in the electron-releasing ability of the --NRH group in the deacetylation of lappaeonitine.