Objective: The Risk-Rescue Rating Scale (RRRS) is generally implemented to predict the lethality of suicide attempts, whereas the Acute Physiology and Chronic Health Evaluation II (APACHE-II) scoring system is applied as an accurate measure of the severity of patient condition of patients admitted to intensive care units (ICUs). Using the RRRS and APACHE-II scores, in this study, we aimed to investigate the factors related to ICU admissions of deliberate self-poisoning (DSP) patients admitted to emergency departments (EDs). Methods: The epidemiologic and psychologic factors, electronic medical records, and laboratory tests of DSP patients were prospectively collected and analyzed. We divided the patients into two groups, an ICU admission group and a non- ICU admission group. Results: This study included 387 patients, 333 (86.0%) of which were in the non-ICU group and 54 (14.0%) in the ICU admission group. Multivariate logistic analysis was conducted to independently associate the ICU admissions with RRRS (odds ratio [OR], 1.40; 95% confidence interval [CI], 1.27-1.55; P<0.01), APACHE-II scores (OR, 1.11; 95% CI, 1.03- 1.21; P=0.01), and amylase values (OR, 1.01; 95% CI, 1.00-1.01; P=0.02). A receiver operating characteristics (ROC) curve analysis of the decision for admission to the ICU yielded the following scores for RRRS and APACHE II―cutoff values of 39.5 and 8.5, sensitivity of 96% and 66.0%, specificity of 74.0% and 75.1%, and area under the ROC curve (AUC) values of 0.95 and 0.74, respectively (P<0.01). Conclusion: The RRRS and APACHE-II scores could be used to determine ICU admissions in DSP patients admitted to the ED.