The topological sub-structural molecular design (TOPS-MODE) approach has been introduced for the study of mutagenic properties. The mutagenicity of 15 dental monomers was studied with this approach obtaining a good quantitative structure-toxicity model. For purposes of comparison, we employed seven different weights in the diagonal entries of the bond matrix in order to select the best TOPS-MODE model. In addition. our best model was compared with a model previously reported in the literature, and proved to be superior. Finally, the TOPS-MODE approach was used to derive the contribution of different fragments to the mutagenicity of all the compounds studied. (C) 2004 Elsevier Ltd. All rights reserved.