en Epidemiology and Causes of Poisoning in patients referred to Loqman Hospital, Tehran, Iran during summer 2010 تخصصي Special پژوهشي Research <b>Background: </b>Poisoning is a serious health problem in the world. In the intentional type, the person may attempt suicide by self-poisoning or may be poisoned by others in a criminal act. The present study was designed to investigate the causes and the frequency of poisoning cases referring to Loqman Hospital, Tehran, Iran, during summer 2010. <br><b>Methods:</b> In this descriptive-analytical study, age, gender, educational level, daily sleep duration, history of physical illness, and type of substance used for poisoning were analyzed by SPSS software. <br><b>Results: </b>Of the 200 poisoned patients, 51% were male and 49% female. 60% of the patients were single. The patients’mean of age was 26.82 years. Minimum age was 14 years and maximum age was 77 years. Most of the patients were graduated from high school and 95.5% of them were living in large cities. Their parents were alive in most cases (92.2%) and 70.5% of them were the first to third child of their family. The person in charge of them was their parents in most cases. The mean daily sleep duration was 7 hours and 72% of the subjects did not have any physical illnesss. Also, 42% of the patients had history of cigarette smoking. Overall, 57% of the patients were poisoned by antidepressant drugs, 31% by narcotic compounds, and remaining 12% by unknown substances. <br><b>Conclusion:</b> Most poisoned cases by antidepressant drugs can be explained by a various of reasons such as availability of the drugs. The findings of this study necessitate more vigilance from physicians in prescribing drugs and community in educating people about drugs. Antidepressant Drugs, Opioid Compounds, Poisoning. Antidepressant Drugs, Opioid Compounds, Poisoning. 642 648 http://ijt.arakmu.ac.ir/browse.php?a_code=A-10-2-95&slc_lang=en&sid=1 Seyed Mahdi Mortazavi سیدمهدی مرتضوی 10031947532846002524 10031947532846002524 No Student of Nursing ,Baghyatallah University of Medical Sciences ,Tehran, Iran. Yahya Haaji یحیی حاجی 10031947532846002525 10031947532846002525 No Faculty of Nursing , Baghyatallah University of Medical Sciences ,Tehran, Iran. Ahmad Khonche احمد خنچه 10031947532846002526 10031947532846002526 No Department of internal medicine Baghyatallah University of Medical Sciences ,Tehran, Iran. Hamidreza Jamilian احمدرضا جمیلیان mjamilian@yahoo.com 10031947532846002527 10031947532846002527 Yes Department of Psychiatry , Arak University of Medical Sciences ,Arak ,Iran.