A pipeline pig for pigging a fluid transporation pipeline, especially one in which a cable or other line is permanently deployed, comprises on a central tubular shaft an array of radial-bristle planar brushes which are spaced apart in planes normal to the axis of the shaft by spacers, and in some cases by groups of sail cloth diaphragms secured between spacers. The brush bristles comprise resilient plastics filaments (preferably nylon) coated with an abrasive material such as carborundum, and have a radial length such that when the pig is inserted in a pipeline, the bristles are deflected and curved rearwardly so that a substantial part of each bristle lies in contact with the internal surface of the pipeline. The leading end of the pig may comprise a deflector cone to facilitate passage of the pig past a cable deployed in a pipeline. The sail cloth diaphragms may be provided with radially extending pleats.