Publisher Summary The use of biomarkers represent a suitable means of correlating data relevant to the concentration of chemical pollutants in marine organisms and alteration of physiology. Such an approach can be a highly informative, cost-effective complement to the chemical monitoring programs developed in the recent years. The objective of biomarker application is to diagnose the exposure and effects of contaminants in order to complete bioassays and the evaluation of chemical contamination levels which have been monitored since 1974 within the French Monitoring Network. Since 1990, field experiences along the Atlantic and Mediterranean coasts has led to the development of a bivalve embryo test and a biomarker of exposure, ethoxyresorufm-o-deethylase (EROD), in the various fish species (dab, dragonet and red mullet). Several biomarkers are also used on a large geographical scale to evaluate the biological and genotoxic effects of marine pollutant near large coastal cities in the northwestern part of the Mediterranean Sea. EROD activities, acetylcholynesterase inhibitions (ACHE), and DNA adducts were respectively studied as metabolic neurotoxic and genotoxic effects within three target species of teleosts—red mullet Mullus barbatus L. 1758 and two type of comber (Serranus hepatus L. 1766 and S. cabrilla L.1766). More recent research concerning mutations in the ras gene, as well as DNA adducts measurement and pathological changes in the teleost fish Callionymus lyra dragonet, has led to the application of a multimarker strategy intended to link effects of early exposure to pollutants with the appearance of more long-term biological events such as mutations and pathologies.