The reaction of 1- nitroso- 2- naphthol with tyrosine was used to study the tyrosine content of sugar beet during its storage and in its products after processing. In order to investigate the influence of different components which are present in sugar beets, the reaction was first applied to molasses (containing many impurities). The re- sults obtained were constant and reproducible indicating that this rapid and ac- curate method is applicable to the determination of the tyrosine present in sugar beets.