Aim of this study was to determine the extent of pollution in the West Black Sea Coast of Turkey by measuring CYP1A associated EROD activity, phase II enzyme, glutathione S-transferase and antioxidant enzymes, catalase and glutathione reductase activities and immunochemical detection of CYP1A protein level in the liver of mullet. The fish samples were caught from six locations having a varying degree of pollution in the West Black Sea Region of Turkey in August 2005, 2006 and 2007. Mullets caught from Zonguldak Harbour, Eregli Harbour and Guluc Stream's Mouth displayed 6-9-fold higher EROD, 2-4-fold higher glutathione S-transferase and 2-3-fold higher catalase activities than the reference site, Amasra. Total polyaromatic hydrocarbon levels in mullets caught from these locations were also significantly higher (2-4-fold) than Amasra. The results Of this Study indicate that Zonguldak Harbour, Eregli Harbour and Guluc Stream are highly Polluted by polycyclic aromatic hydrocarbons and related contaminants. (C) 2009 Elsevier Ltd. All rights reserved.