Trans-chalcone (1,3-diphenyl-2-propen-1-one), a biphenolic core structure of flavonoids precursor was tested for inhibitory activity toward alpha-amylase. Porcine pancreatic alpha-amylase was observed to be effectively inhibited by this compound, which showed competitive behavior with a K(i) of 48 μM. Soluble starch (the natural substrate of the enzyme) was used in this study in order to obtain more realistic results. The possible binding mode of the compound was assessed in silico, and the two residues Trp59, and Tyr62 were proposed as main interacting residues with trans-chalcone. In conclusion, this compound could be used to design effective inhibitors of alpha-amylase.