en Clinical Neuroscience Clinical Neuroscience Original Original <strong>Introduction</strong>: Oxidative stress plays a critical role in the pathogenesis of neurodegenerative and neuropsychiatric disorders. However, its role in suicidal behavior has not been clarified yet. Consequently, we aimed to evaluate the oxidant-antioxidant status in the serum of suicide attempters in Ilam city.&nbsp;<br> <strong>Methods</strong>: Fifty suicide attempters and 40 control subjects (volunteers) aged 18-35 years were studied in the current experiment. To consider the oxidant-antioxidant status, serum levels of Malondialdehyde (MDA), Nitric Oxide (NO), Superoxide Dismutase (SOD), and the Total Antioxidant Capacity (TAC) were measured.&nbsp;<br> <strong>Results</strong>: Serum levels of SOD and TAC were significantly lower in the suicide attempters group compared to the controls. Furthermore, serum NO level was significantly higher in the suicide attempters compared to the control groups. Interestingly, the serum level of MDA was significantly lower in the suicide attempters compared to the control groups.<br> <strong>Conclusion</strong>: The oxidative stress without MDA elevation, detected in suicide attempters, can be considered a biochemical hallmark in suicide behavior.&nbsp; Suicide behavior, Oxidative stress, TAC, MDA, SOD 667 674 http://bcn.iums.ac.ir/browse.php?a_code=A-10-1917-1&slc_lang=en&sid=1 Mahin Oshnokhah m.oshnokhah@gmail.com 13700319475328460039400 13700319475328460039400 No Department of Clinical Biochemistry, School of Medicine, Ilam University of Medical Sciences, Ilam, Iran. Maryam Bagheri maryam.bagheri@medilam.ac.ir 13700319475328460039401 13700319475328460039401 No Department of Physiology, School of Medicine, Ilam University of Medical Sciences, Ilam, Iran. Hori Ghaneialvar ghaneihuri@yahoo.com 13700319475328460039402 13700319475328460039402 No Department of Clinical Biochemistry, School of Medicine, Ilam University of Medical Sciences, Ilam, Iran. Karimeh Haghani Haghani.bio@gmail.com 13700319475328460039403 13700319475328460039403 No Department of Clinical Biochemistry, School of Medicine, Ilam University of Medical Sciences, Ilam, Iran. Ali Khorshidi khorshidi-a@medilam.ac.ir 13700319475328460039404 13700319475328460039404 No Department of Epidemiology, Ilam University of Medical Sciences, Ilam, Iran. Ali Shahbazi shahbazial@yahoo.com 13700319475328460039405 13700319475328460039405 No Department of Neuroscience, School of Medicine, Iran University of Medical Sciences, Tehran, Iran. Sajjad Salari sajjad.salari@medilam.ac.ir 13700319475328460039406 13700319475328460039406 Yes Department of Physiology, School of Medicine, Ilam University of Medical Sciences, Ilam, Iran.