BACKGROUND Elderly persons with acute poisoning in the emergency department (ED) and prognostic factors of outcomes have not been well addressed in previous research. This study aimed to investigate the characteristics of elderly patients with acute poisoning visiting the ED, and to identify the possible predictive factors of mortality. METHODS Patients aged > or = 65 years with acute poisoning who visited the ED in Taipei Veterans General Hospital from January 1, 2006 through to September 30, 2008 were enrolled in the study. We collected demographic information on underlying diseases, initial presentations, causes and toxic substances, complications, dispositions, and outcomes. Analyses were conducted among different groups categorized according to age, suicide attempt, and outcome. Multiple logistic regression was applied to identify possible predictive clinical factors influencing mortality in the elderly with acute poisoning. RESULTS A total of 250 patients were enrolled in the study, with a mean age of 77 years and male predominance. The most common cause of intoxication was unintentional poisoning. Medication accounted for 57.6% of poisonous substances, of which benzodiazepine was the most common drug, followed by warfarin. The overall mortality rate was 9.6%. The average length of stay in the ED increased significantly in the old (65-74 years), very old (75-84 years) and extremely old (> or = 85 years) groups. Suicide attempt patients experienced more complications including respiratory failure, aspiration pneumonia, hypotension and mortality. Three clinical predictive factors of mortality were identified: herbicide poisoning, hypotension and respiratory failure upon presentation. CONCLUSIONS Our results demonstrated that elderly patients with acute poisoning had a mortality rate of 9.6%. Suicide attempts resulted in more serious complications. The risk factors for mortality were herbicide intoxication, hypotension and respiratory failure.