Abstract: Objectives: This study aimed to describe the clinical and procedural characteristics of drug poisoning, to examine procedural differences between drug poisoning repeaters and non-repeaters, and to estimate the costs of drug poisoning.Methods: A retrospective cohort study of a nationally representative sample of 6585 inpatients with drug poisoning was conducted, using the administrative database of the Diagnosis Procedure Combination/Per-Diem Payment System in 2008.Results: Although only 3% of patients required surgery and 65% were discharged from the hospitals within 3 days, greater than 30% were admitted to tertiary emergency care (i.e., high-level emergency care) centers that provide care to severely ill and trauma patients who require intensive care. Only 30% of patients received psychiatric consultation during hospitalization. In addition, repeaters were less likely to be admitted to hospitals by ambulance (67% vs. 76%) and more likely to be discharged within 3 days (77% vs. 65%) than non-repeaters. The annual economic burden of drug poisoning in Japan was $66 million (¥7.7 billion), with the population aged 20–39 years accounting for 50% of these costs.Conclusion: This study highlights the need for optimally allocating resources and improving prevention strategies.