The mutagenicity and cytotoxicity of hexavalent chromium (K2Cr2O7) were assessed by a Salmonella microsuspension bioassay, in order to define standard mutagenicity dose-response curves for this compound with TA97a, TA98, TA100 and TA102 Salmonella typhimurium strains, in the presence and absence of the exogenous metabolism fraction (S9). All the Salmonella strains tested were more or less efficiently reverted by Cr(VI) in the absence of S9 mix, with the following ranking of sensitivity available with the necessary concentration of potassium dichromate (µg) to double the number of revertant colonies in the negative control: TA98, TA100, TA97a, TA102. After metabolism the number of revertant colonies decreased in all strains studied, but positivity remained for TA97a and TA100 strains or indications of this mutagenicity in the TA98 and TA102 strains. The Salmonella microsuspension bioassay showed response sensitivity to detect mutagenicity induced by K2Cr2O7, was an appropriate assay to study environmental samples in areas which could be contaminated by chromium VI