[Show abstract][Hide abstract] ABSTRACT: In December 2009 seven male sperm whales (Physeter macrocephalus) stranded along the Adriatic coast of Southern Italy. Genetic and photo-identification data indicated that these specimens belonged to the Mediterranean Sea population. Complete necropsies were performed on the three best preserved animals. Blubber and muscle samples were collected from all seven specimens for contaminants analysis (DDTs, PCBs and PAHs) and biomarker responses (CYP1A1 and CYP2B) were evaluated from the three better preserved animals using western blot analysis. Fibroblast cell cultures from two specimens were set up by culturing cell lines from integument tissue, to explore the susceptibility of these marine mammals to different xenobiotic compounds. The levels of CYP1A1 and CYP2B, proteins that are induced by some POPs (DDTs and PCBs) and PAHs were detected using the indirect immunofluorescence assay. The results showed relatively high levels of contaminants, in particular from organochlorine xenobiotics, and strong responses of CYP1A1 and CYP2B reflecting toxicological stress of these sperm whales. This is not considered to be their cause of death, but may have contributed to lowering the defences of their immune system. Copyright (c) 2014 John Wiley & Sons, Ltd.