Industrial wastewaters quality became a target for the environmental toxicity assessment nowadays. When there are issues with complex effluents for which many chemicals cannot be quantified and/or interactive effects are likely to be significant, the use of bioassays with different test species becomes a more reliable way in the assessment of toxicity. Ecotoxicity evaluation of the several samples shows different behaviours among the groups tested, e.g. bacteria, algae, microcrustaceans and macrophyte. In some cases for the same sample the highest toxicity is shown by one of the test organisms while the remaining ones show no toxicity. The opposite case also occurs.