Diffuse reflectance spectrophotometry in the ultraviolet, visible and near-infrared (UV-vis-NIR) range is becoming a widely-used tool for the non-invasive analysis of cultural heritage objects, especially in its variant with optical fibres, commonly dubbed FORS (Fibre Optic Reflectance Spectroscopy). It is especially useful to study objects such as medieval manuscripts for which sampling is prohibited by current conservation standards. This brief describes the most common types of application of FORS in the analysis of cultural heritage objects; it also illustrates the instrumentation used and the main advantages and limitations of the technique.