Background: Dietary anthocyanins are plant pigments which occur with different chemical structures, being widely present in fruits and in many vegetables, are claimed to be beneficial for human health. The bioavailability of anthocyanins is the key factor influencing their health benefits. Objective: Herein, the molecular structure-affinity relationship of anthocyanin-human serum albumin interaction was investigated. Methods: Fluorescence quenching method was applied to determine the binding affinities of anthocyanins for human serum albumin. Results: Demethylation of the methoxyl groups in anthocyanins enhanced the binding affinities. The number and position of the hydroxyl groups on ring [B] affect the affinities of anthocyanins for human serum albumin. The glycosylation of hydroxyl groups on ring [C] enhanced their binding affinities for human serum albumin. Conclusions:Anthocyanidins and anthocyanins, showdifferent characteristics for their binding to human serum albumin when the methoxyl groups on the ring B are demethylated or hydroxylated. © 2018 IOS Press and the authors. All rights reserved.