A critical appraisal is made of the part played by lichens in the deterioration of a wide range of archaeological materials in Italy. Stone and art-works in exposed and partially enclosed environments were examined to identify those most vulnerable to attack. Assessment was made of the relationships between particular species and the physical and chemical nature of their substrata, to estlabish those species responsible for disfigurement and those causing damage. Particular attention was paid to recent environmental changes conducive to lichen invasion of terracotta, mortar and painted plaster. References.