Numerous sources of information were compared to appraise and then map fire risks in the Limousin region (France). This risk map was the first to be plotted for an entire region using a geographical information system. Three main general principles were chosen: available or easily obtainable data should be used; every parameter should be expressed quantitatively; the parameters should be expressed in a logical manner; fire risk should be calculated as a combination of risk of ignition and risk of spread (see diagram). High-risk zones are determined by superimposing 13 maps (2 for climate, 3 for demography, 2 for statistics, 2 for intervention and 4 for vegetation. The application was developed using version 4.1 of GRASS freeware distributed by the US army. Ground resolution is 20 metres.