Epidemiologic studies have suggested that exposure to solvent-based materials in the painting trades is associated with an increased cancer risk. In order to determine if the solvent exposures of current union members of the International Brotherhood of Painters and Allied Tradesman (IBPAT) are associated with a genotoxic risk, we have measured the sister chromatid exchange (SCE) frequency in their peripheral blood lymphocytes. Previous reports have shown that chronic solvent exposure of these workers does not elevate SCE frequencies. We now report that acute exposure, estimated by the number of days worked over the month prior to venipuncture, is associated with elevated SCE levels in currently smoking workers. No elevation in SCE was associated with similar recent exposure in nonsmoking, solvent-exposed painters.