The South-westem part of Sardinia is characterised by exposure of Palaeozoic sediments representing the oldest rocks in Italy. Approximately a quarter of this area, named Sulcis-Iglesiente, is occupied by Cambrian sequences, reaching a visible thickness of over 2000 metres. One third of the Cambrian rocks is constituted of limestones and dolomites, intensely mineralised and karstified, forming one of the most interesting karstic areas of Europe. In the present paper the authors have described 24 karstic geosites of particular interest, of which 16 in the Iglesiente area and the remaining 8 in Sulcis. These can be classified as caves (9), karst landscapes (7), karstic springs (4), paleokarst and mineralization phenomena (4).