Purpose: The use of flumazenil administration in the emergency department is still controversial because of concerns about adverse effects. The present study was conducted to re-evaluate the risk-benefit ratio associated with flumazenil administration to patients suspected of having acute hypnotics and sedatives poisoning in the emergency department. Methods: A retrospective chart review study was conducted for patients whose final diagnoses were “poisoning” and “benzodiazepine” or “sedatives-hypnotics” from Mar. 2006 to Feb. 2015. The basal characteristics of the patients, including past medical history, ingredients and dose of ingested drug and co-ingested drugs were investigated. For patients administered flumazenil, responsiveness and time from admission to flumazenil administration were investigated with supplement. All collected data were analyzed in aspect terms of risk/benefit. Results: A total of 678 patients were included in our study. Benzodiazepine was the most common sedative/hypnotic drug prescribed, and the frequency of prescription continuously increased. The proportion of TCA as co-ingestion decreased from 13.1% to 3.9% in patients with acute sedative/hypnotic poisoning. Flumazenil was administered to 55 patients (8.1%), of which 29 patients (52.7%) were applied to contraindications. Fifty-three patients (96.4%) showed positive responsiveness, including partial responsiveness after flumazenil administration. No severe adverse events were identified. Conclusion: Based on the current trends in prescription patterns for sedative/hypnotic drugs, increased use of non- TCA antidepressants, and responsiveness to administration of flumazenil, benefit seemed weighted more in this study, although the observed benefits were based on limited results. Further prospective multicenter studies will be needed to optimize benefit-risk ratio.