The invention relates to a device for dewatering and washing fibre stock suspensions with two counter-rotating rolls (2, 3), a stock feed (4, 5) and a stock discharge (6). It is mainly characterized by the headbox (4, 5) at the two rolls (2, 3) being arranged separately in the lower section of the rolls (2, 3), and a discharge screw (6) being foreseen for discharge of the filter mat below the gap between the two rolls (2, 3) and a washing zone (9″, 10″) in the upper part of the rolls (2, 3).