en تخصصي Special پژوهشي Research <strong>Background:</strong> Nicotine is a toxic compound in the cigarette smoke and has destructive effects on various human organs. Astaxanthin is a carotenoid with high antioxidant property. In this study, we investigated the protective effects of astaxanthin against nicotine-induced toxicity in mice testes.<br> <strong>Methods:</strong> Forty-two inbred balb/c male mice were divided into six groups:<em>Group 1</em>, received 1 ml normal saline daily; <em>Group 2</em>, received nicotine (1.5mg/kg); <em>Group 3</em>, received astaxanthin (25mg/kg); <em>Group 4</em>, received astaxanthin (50mg/kg); <em>Group 5</em>, received astaxanthin (25mg/kg) plus nicotine (1.5mg/kg); and <em>group 6</em>, received astaxanthin (50mg/kg) plus nicotine (1.5mg/kg). After collecting testes samples, microscopic slides were prepared at the School of Veterinary Medicine, University of Mashhad, and the prepared slides were examined under light microscopy.<br> <strong>Results:</strong> The histological structures of the testes were normal in the control group and those receiving astaxanthin, regardless of nicotine (groups 3, 4, 5 & 6).&nbsp; However, group 2 that received only nicotine, showed transformed testicular histology with severe hemorrhage.<br> <strong>Conclusion:</strong> Based on the results, nicotine caused harmful effects on the mice testes and astaxanthin appeared to protect the organs against the toxic effects of nicotine. Astaxanthin, Balb/c mice, Nicotine toxicity, Testicular Hemorrhage 41 44 http://ijt.arakmu.ac.ir/browse.php?a_code=A-10-540-4&slc_lang=en&sid=1 Bashir Sobhani 100319475328460011383 100319475328460011383 Yes PhD student of Veterinary Medicine, Ferdowsi University of Mashhad. Mashhad, Iran. Sahar Roomiani 100319475328460011384 100319475328460011384 No Department of Basic Science, Faculty of Veterinary Medicine, University of Shushtar. Khuzestan, Iran. Zahra Ahmadi 100319475328460011385 100319475328460011385 No Department of Basic Science, Faculty of Veterinary Medicine, University of Shushtar. Khuzestan, Iran. Milad Ashrafizadeh dvm.milad73@yahoo.com 100319475328460011386 100319475328460011386 No Department of Basic Science, Faculty of Veterinary Medicine, University of Tabriz. Tabriz, Iran.