The beta-D-gentiobioside [beta-D-glucopyranosyl(1 --> 6)-beta-D-glucopyranoside] of 3-hydroxy-beta-ionol has been isolated and characterized in quince (Cydonia oblonga) fruit through spectral and chemical studies. Model experiments carried out with this new natural compound revealed its important role as precursor of a number of C-13-norisoprenoid flavour compounds of quince essential oil.