With many important artistic works and documents made of paper, and thus susceptible to biodeterioration by fungi, research is required in an effort to replace toxic chemical products with other more benign ones. In this work the antifungal effect of methyl and propyl paraben mixtures at different concentrations was evaluated. The fungi used in the experiments were a Cladosporium species and Penicillium corylophilum, both of which are well known as paper-biodeteriorating fungi. The results ;demonstrate that a mixture of 0.5% methyl paraben and 1% propyl paraben, in 85% ethanolic solution, is the lowest concentration necessary to provide an efficient antifungal action. A deacidification agent, 5% calcium propionate, was added to this mixture to produce a multi-purpose formulation to treat acidification and fungal contamination of paper documents. Tests carried out on paper samples before and after application of this mixture showed only a minor increase in yellowing and a slight decrease in tensile strength, while substantially raising the pH, and thus the alkaline reserve, and also a slight increase in the percentage of deformation. (C) 2008 Elsevier Ltd. All rights reserved.