Abstract: A pipeline inspection apparatus includes a pipeline pig which has a shaker for causing the pig to vibrate in one or more of the vertical, longitudinal, lateral, bending and torsional senses. The vibrations are transmitted into the wall of a pipeline through which the pig is moved and the vibration response of the pipeline is measured by accelerometers in the pig for detecting one or more of the vertical, longitudinal, lateral, bending and torsional motions of the pig. A data acquisition system and computer are used. For displaying and/or recording the measured data in a form which can be used to identify variations in the structural condition of the pipeline.