The new alkaloid folidine with mp 148-149°C (acetone-petroleum ether) has been isolated from the epigeal part of the plant Haplophyllum foliosum Vved., and on the basis of spectral characteristics and passage to the known alkaloid folifidine (8-hydroxy-4-methoxy-1-methyl-2-quinoline) its structure has been established as 4-methoxy-1-methyl-8-(2′-oxo-3′-methylbutoxy)-2-quinolone. © 1986 Plenum Publishing Corporation.