BACKGROUND: The goal of this study was to analyze the process and characteristics of withholding or withdrawal of life support (WLS) in Korean intensive care units (ICUs). METHODS: This was a single-centered retrospective analysis of patients who died in the ICUs of a tertiary hospital in Korea from January to December 2012. WLS informed consents and clinical data were analyzed. RESULTS: Of 285 deaths during the study period, informed consents for WLS were obtained from 228 patients (80.0%). All WLS decisions were made by family members after the patient's loss of decision-making capacity. Decisions were made most frequently by the patient's son (50.6%). Patients in the WLS group were older than those in the non-WLS group, and older age was associated with the WLS decision. Thirty-seven patients (16.2%) died within one hour of WLS approval, and 182 patients (79.8%) died on the day of WLS approval. The most frequently withheld life support modality was chest compression (100%), followed by defibrillation (95.9%) and pacemaker insertion (63.3%). CONCLUSIONS: Aggressive and invasive life support measures were those most frequently withheld or withdrawn by decision-makers in Korean ICUs. The most common proxy was the son, rather than the spouse.