No abstracts are to be cited without prior reference to the author.A previous study performed in four areas along the Iberian Mediterranean coast suggested lower DNA liver integrity in red mullet (Mullus barbatus) caught from Cartagena (southeast Spain) in comparison with the other areas (Delta Ebro, Valencia, and Guardamar), though significant differences were not demonstrated. Here we present the results of a study on other types of genotoxic measurements in red mullet. These include erythrocyte micronuclei (MN) frequency and other nuclei abnormalities in peripheral blood samples (n > 5000 blood cells/fish) of red mullet (n = [19–34]) caught in seven different areas of the Iberian coast (Barcelona, Tarragona, Delta Ebro, Valencia, Cartagena, Almería, and Málaga). Mean MN frequency (expressed per 1000 cells/individual fish) was significantly higher (1.26; p < 0.001) in fish caught from Barcelona than in those from the other areas (0.23–0.59). However, other kinds of abnormalities such as binucleated and lobed nuclei were more frequently observed in fish from Cartagena and Almería. On the basis of our findings, and the fact that the use of this type of biomarker is relatively cheap and blood can be sampled easily on site, this biomarker will be routinely incorporated in the Spanish biomonitoring programme of marine contamination on the Mediterranean coast.