he potential genotoxic effects induced by drinking water samples in prokaryotic (Salmonella) and lower eukaryotic (yeast) cells and the DNA damage in human hepatoma cell line with the results of physico-chemical analyses. Since nitrates and pesticides enter the water systems by agricultural activities on land surfaces trough fertilization and crop protection processes and since the chosen sampling points of drinking water, based on previous analyses,16 showed elevated levels of nitrates and pesticides (i.e. atrazine), our interest focused mainly in evaluating the genotoxicity potential of chosen parameters which are also included in regular monitoring of drinking waters according to Slovenian regulations.