Abstract: Several flavonols were chemically transformed upon treatment by Trametes versicolor laccase; the majority of the major oxidation products were isolated (HPLC) as pure compounds and their structures unambiguously established through spectroscopic methods (HPLC-MS), when possible. In some cases, compounds were difficult to obtain either completely pure or in sufficient amounts. In these cases, structural hypotheses were formed on the basis of the HPLC-MS fragmentations. Correlation between the structure of the oxidation products and the substitution pattern of the starting materials revealed mechanistic features of the transformation.