Background: Acute poisoning is a significant and preventable cause of mortality among children internationally. The aims of this study were to assess the case fatality rate of children admitted to an inner-city hospital for acute poisoning and to compare the demographics and source of poisoning of fatal cases.Methods: This was a retrospective review of patient data recorded in the Hospital Information System for Loghman Hakim Hospital, that is, the central referral hospital for poisoning in Tehran, Iran. We searched Hospital Information System for all admissions for poisoning in children (age, 0--12 years) over the 10-year period from March 2010 to March 2020, and all cases were included in the analysis. We determined the case fatality rate by dividing the number of fatal cases by the number of included cases.Results: Of 8158 children admitted for poisoning, 28 cases (0.3%) died, among whom 19 (67.9%) were boys and 9 (32.1%) girls. The median age was 42 months, ranging from 2 to 144 months. Twenty-two cases (78.6%) were 0 to 5 years old. The most common cause of mortality in acute poisoning was methadone (n = 13, 46.4%), followed by raw opium (n = 5, 17.9%), aluminum phosphide, carbon monoxide, and wild mushrooms (n = 2 deaths each, 7.1%). Tramadol, colchicine, and petroleum accounted for 1 death each (3.6%).Conclusions: Mortality from unintentional poisoning disproportionately affects children younger than 5 years. Opioids (ie, methadone, opium, tramadol) accounted for two thirds of deaths in our sample. Our findings highlight the importance of educating parents that any toxic materials (licit or illicit) must be stored out of reach for children.