Studies the main deterioration factors affecting prehistoric rock paintings and drawings. These include muddy deposits from human or natural origin, concretions, traces of rubbing, soot deposits, and graffiti. Examples of conservation treatment carried out in prehistoric caves from the south of France are presented including mechanical removal of muddy concretions, application of paper pulp compresses for the removal of the soot; mechanical removal of the calcite, protection from running water by installation of elastomer cushions.