Using 15N it is shown that 91% of the nitrogen of the alkaloid gentianine isolated from Gentiana lutea originates from the ammonia added during the isolation. Gentianine thus is mainly an artifact which, according to chromatographic evidence, is formed from gentiopicroside. These findings are extended to other Gentiana species by chromatographic techniques. The biosynthesis of gentiopicroside is discussed and some evidence against an acetate pathway and for a mevalonate pathway is presented.