Rapidly increasing knowledge about the high complexity of food aromas requires selection or ranking procedures as to the importance of the particular components for flavour impression. For this purpose the concept of aroma values has been discussed which calculates quantitative data in connection with aroma effectiveness of the compounds. The simplification of the concept with respect to the practical application, however, can change the natural system and lead to erroneous conclusions. There are not only interactions between aroma substances of sensoricphysiological character which may not be ignored. Physical conditions like lipid content, distribution of aroma compounds between aqueous and lipid phase or the sorption of volatile substances to the polymer nutrients in foodstuffs are of influence, too.