Abstract. Maps of areas with different vulnerability degrees are an integral part of environmental protection and management policies. It is difficult to assess the intrinsic vulnerability of karst areas since the stage and type of karst structure development and its related underground discharge behaviour are not easy to determine. Therefore, some improvements, which take into account dolines, caves and superficial lineament arrangement, have been integrated into the SINTACS R5 method and applied to a karst area of the south-eastern Murge (Apulia, southern Italy). The proposed approach integrates the SINTACS model giving more weight to morphological and structural data; in particular the following parameters have been modified: depth to groundwater, effective infiltration action, unsaturated zone attenuation capacity and soil/overburden attenuation capacity. Effective hydrogeological and impacting situations are also arranged using superficial lineaments and karst density. In order to verify the reliability of the modified procedure, a comparison is made with the original SINTACS R5 index evaluated in the same area. The results of both SINTACS index maps are compared with karst and structural features identified in the area and with groundwater nitrate concentrations recorded in wells. The best fitting SINTACS map is then overlaid by the layout of potential pollution centres providing a complete map of the pollution risk in the area.