The invention concerns an enzymatic method for making oenological tannins starting with lumps of wood and an enzymatic method for transforming tannins into tannins for wine-making purposes. The inventive method comprises a step which consists in contacting the lumps of wood or tannins with an aqueous solution comprising a composition containing enzymes of the cellulase class. The invention also concerns an enzymatic composition mainly consisting of enzyme of the cellulase class for making oenological tannins, comprising an endocellulase activity, a xylanase activity a .beta.-mannanase and/or .alpha.-amylase activity.