Two closely related species: Melilotus alba and M. officinalis were compared in respect to chromatographically separated and visualized flavonoids. Several compounds were common for both species. Taking into account that phenolic compounds are genetically strictly controlled and not sensitive to environmental influences, the presence of characteristic compounds for each species confirmed their taxonomic values and differences. Key words: Melilotus alba, M. officinalis, TLC, phenolic compounds, genetic differences