Abstract: The invention relates to a device for collecting filtrate samples from a pulp suspension. It comprises a piston rod (3) which, when actuated by a cylinder (2), can reciprocate inside a jacket (5) and which is provided with a filter (4) arranged in an extended position to catch a sample. The filter (4) consists of a wire (6) having a triangular cross-section, the turns (8) of the wire being located close to each other and having their base surface (9) directed outwards and their converging surfaces directed inwards towards the center of the filter (4). During its retracting movement into the jacket the filter (4) is cleaned in the way that fibres which have got stuck on the filter are scraped away by the jacket.