en عمومى General پژوهشي Research <strong>Background:</strong> We examined the effects of phenanthrene (Phe) on hematological parameters of yellowfin seabream (<em>Acanthopagrus latus</em>).<br> <strong>Methods:</strong> The research was carried out in Jan 2016 at Khorramshahr University of Marine Science and Technology, Khorramshahr, Iran. Fish were injected with different concentrations (0, 2, 20 and 40 mg/kg) of Phe and blood, samples were taken from fish 1, 4, 7 and 14 d after injection.<br> <strong>Results:</strong> Results of Phe-treated fish showed a decrease in red blood cell and white blood cell counts, hematocrit amount after 4 d and in hemoglobin concentration after 7 d (<em>P</em><0.05). Mean corpuscular hemoglobin concentration was enhanced in fish exposed to Phe up to day 4 (<em>P</em><0.05). Phe-exposed fish showed an increase in the <em>percentage of</em> neutrophils with a decrease in the <em>percentage of</em> lymphocytes (<em>P</em><0.05) and did not represent any effects on <em>percentage of</em> monocytes and eosinophils, mean corpuscular volume and mean corpuscular hemoglobin concentration.<br> <strong>Conclusion:</strong> Changes in hematological parameters after exposure to Phe result in a decrease of non-specific immunity. Fish, Polycyclic aromatic hydrocarbons, Toxicity, blood cells Blood Cells, Fish, Polycyclic Aromatic Hydrocarbons, Toxicity 47 52 http://ijt.arakmu.ac.ir/browse.php?a_code=A-10-446-3&slc_lang=en&sid=1 Mehrnaz Shirmohammadi shirmohammadim@yahoo.com 10031947532846006764 10031947532846006764 Yes Department of Marine Biology, Faculty of Marine Science, Khorramshahr University of Marine Science and Technology, Khorramshahr, Iran. Negin Salamat 10031947532846006765 10031947532846006765 No Department of Marine Biology, Faculty of Marine Science, Khorramshahr University of Marine Science and Technology, Khorramshahr, Iran. Mohammad Taghi Ronagh 10031947532846006766 10031947532846006766 No Department of Marine Biology, Faculty of Marine Science, Khorramshahr University of Marine Science and Technology, Khorramshahr, Iran. Abdolali Movahedinia 10031947532846006767 10031947532846006767 No Department of Marine Biology, Faculty of Marine Science, Khorramshahr University of Marine Science and Technology, Khorramshahr, Iran. Gholamreza Hamidian 10031947532846006768 10031947532846006768 No Department of Basic Sciences, Faculty of Veterinary Medicine, University of Tabriz, Tabriz, Iran.