Some species of natural unsaturated hydrocarbon phenols have been reported to have anti-biofouling effect. They have potential industrial applications where bacterial contamination should be avoided. We fabricated polydimethylsiloxane (PDMS) matrices impregnated with unsaturated hydrocarbon phenols: urushiol from the sap of natural lacquer tree and a mixture of cardol and cardanol from refined cashew nut shell liquid (CNSL). Their anti-fouling property has been tested by crystal violet staining method. Urushiol-impregnated PDMS matrix showed excellent antimicrobial property to both Escherichia coli and Saccharomyces cerevisiae. With the concentrations of cardanol higher than a certain critical value, CNSL-impregnated PDMS matrix also showed anti-biofouling effect for E. coli and S. cerevisiae. (C) 2008 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.