The ILO International Classification of Radiographs of Pneumoconioses is a powerful tool used throughout the world to improve workers’ health surveillance, conduct epidemiological research and make comparisons of statistical data. Some countries have established legal requirements for use of the Classification in the assessment of compensation claims, although the Classification was not originally designed for this purpose. The value of the Classification depends critically on the consistency with which users apply the Guidelines published by the ILO and the standard radiographs that accompany those Guidelines.