Abstract: A screen system intended for the screening of wood chips, comprising one or several screening faces (2,3) placed one above the other as well as a bottom face (4) placed underneath said screening faces. The screening faces (2,3) are connected to members (10) that produce the screening movement. The bottom face (4) is made of a flexible material and is displaceable relative its support structure (6) so that the bottom face is deformed to prevent the adherence of materials thereto. Most appropriately, the width of the bottom face (5) is larger than the distance between the support structures (6) placed at its sides, whereby the middle portion of the bottom face (5) is hanging down lower than its sides.