The aim of our study was to investigate the etiological and demographical characteristics of acute adult poisoning cases admitted to a university hospital in Tabriz, Iran. This retrospective study was performed on 1342 poisoning admissions to a university hospital from 2003 to 2005, by data collection from the medical records of patients. Poisonings were 5.40% of the total admissions. There was a predominance of female patients (55.7%) compared to male patients (44.3%) with a female-to-male ratio of 1.2:1. Most poisonings occurred in the age range of 11–20 years (38.9%). Drugs were the most common cause of poisonings (60.8%). Among the drug poisonings, benzodiazepines (40.31%) were the most frequent agents, followed by antidepressants (31.98%). The seasonal distribution in poisoning patients suggested a peak in spring (28%) and summer (27.5%). In 9.8% of cases accidental and in 90.2% intentional poisonings were evident. Most suicide attempts were made by women (58.51%) and unmarried people (51.4%).The mean duration of hospitalization was 3.02 ± 2.8 days. There were 28 (2.3%) deaths; the majority (13 cases) was due to pesticides. This was a university hospital-based study, so these results may not be representative of the general population. Despite this drawback, these data still provide important information on the characteristics of the poisoning in this part of Iran. To prevent such poisonings, the community education about the danger of central nervous system-acting drugs and reducing the exposure period of people to pesticides are recommended.