In this study, water and sediments from the Porsuk River were investigated for their potential mutagenicity in Salmonella typhimurium TA 98 and TA 100 strains by performing Ames test (plate incorporation assay) without metabolic activation. Different columns of XAD 4 and XAD 16 were used to fractionate the water samples. Positive results in XAD 4 extracts of water samples were obtained for TA 98 in two of these stations. Extracts of the sediment samples were assayed in five different doses of concentrations and mutagenic results were obtained for both of the two strains in different sampling sites. Total metal concentrations in the stream sediment samples were determined by atomic absorption spectrophotometry (AAS) in order to explain some of these mutagenic results. The presence of mutagens causing frameshift and base-pair substitution mutations in water and sediments of the Porsuk River was suggested by the results and this mutagenicity was discussed. (C) 2004 Elsevier B.V. All rights reserved.