Key sentinel species are employed to monitor biological effects of pollution and assess the quality of ecosystems. Nevertheless, ecotoxicogenomic studies have to face the problem of the lack of genetic information available for toxicologically relevant species. The thicklip grey mullet (Chelon labrosus), a suitable sentinel of pollution able to survive heavily polluted marine/estuarine waters in southern Europe was selected. A multitissue RNA extraction was performed (liver, brain, gonad and gill) cDNA normalised (Evrogen) and completed 1 full plate sequencing-run of (454-roche). Finally, a custom Agilent microarray was generated to study gene transcription profiles in laboratory exposure experiments and in pollution monitoring programs.