The possible effects of wastewater treatment products on mussels (Mytilus galloprovincialis) were studied. Three common pollution biomarkers were used: neutral red retention assay, malondialdehyde contents and DNA damage through comet assay. Two groups of mussels were treated in the laboratory for 25 days with 20 and 40 %v/v of treated wastewater collected after chlorination, the control mussels formed a third group. The results showed statistically significantly lower neutral red retention times, higher malondialdehyde contents and higher formation of single-stranded DNA fragments in the mussels exposed at both treated wastewater concentrations compared to the controls.