Background: The rate of suicide by carbon monoxide (CO) poisoning is increasing rapidly in Korea. In this study, we aimed to investigate the clinical characteristics of suicide attempters in Korea and to identify risk groups for choosing CO poisoning as a suicide method. Methods: Patients who visited the emergency department after attempting suicide between April 2017 and June 2019 were included in this study. We reviewed the medical records and evaluated the demographic and clinical data of suicide attempters. Cross-tabulation analyses and multivariable logistic regression analyses were performed. Results: Statistically significant risk groups for suicide by CO poisoning were men (odds ratios [OR], 1.71), those who were 25-44 years of age (OR, 7.35), those with no psychiatric history (OR, 2.12), and those who made a suicide plan (OR, 7.70). Among suicide attempters grouped according to psychiatric diagnoses, those with adjustment disorders were most likely and those with psychosis were least likely to choose CO poisoning as the suicide method. Conclusion To prevent a CO poisoning suicide attempt, it seems warranted to develop a tool to screen patients for suicide risk as part of a regular health checkup so that early intervention can be provided.