Samples of stone artifacts and fresco surfaces damaged from microbial attack were studied. To evaluate the microbial damaging process on the basis of biochemical analyses, the following areas were studied: 1) the relation between the entity of the microbial attack and enzymic activities inside the damaged substrate; 2) biochemical methods to evaluate the stone pollution; and 3) preparation of antibiograms to evaluate the action of some biocides. -- AATA