Raman spectroscopy is intensively used in biology as it is a non-destructive and non-invasive analytical technique. Several studies have been carried out for medical application such as the development of cellular markers of carcinogenesis and oxidative stress as well as the detection of pathogenic bacteria . In the environmental field, this technique has mostly been used for the detection of microplastic or nanoparticules in organism. However, only few studies have focused on the assessment of toxic effects using Raman spectroscopy, reporting its ability to discriminate copper-tolerant yeast isolated from contaminated soil and by monitoring arsenic toxicity on bacteria . The European Water Framework Directive (WFD) and the Marine Strategy Framework Directive (MSFD) both aim to achieve and maintain a good general water status by 2027. For this, an assessment of the environmental status is necessary, regarding chemical pollution and their effects on living organisms. In this context we propose to use Raman spectroscopy as a diagnostic tool of toxic impact on marine invertebrates. To test this hypothesis, mussels (Mytilus edulis) were exposed to two concentrations of cadmium (50 and 500 µg/L), in parallel with controls, for one week. Then, the gills, the mantle were analyzed with Raman microspectroscopy. Results show that it is possible to discriminate the mantle of the exposed mussels compared to the controls, as well as to differentiate the two concentrations of exposure.