PurposeLife-sustaining treatment (LST) decisions for patients and caregivers at the end-of-life (EOL) process are supported by the “Act on Hospice and Palliative Care and Decisions on LST for Patients at the EOL,” enforced in February 2018. It remains unclear whether the act changes EOL decisions and LST implementation in clinical practice. For this study, we investigated patients’ decision-making regarding LSTs during the EOL process since the act’s enforcement.Materials and MethodsRetrospective reviews were conducted on adult patients who were able to decide to terminate LST and died at Seoul National University Hospital between February 5, 2018, and February 5, 2019. We examined demographics, who made the decisions, the type and date of documentation confirming patient's LST, and whether the LST was withheld or withdrawn.ResultsOf 809 patients who were enrolled, 29% (n=231) completed forms regarding LST themselves, and 71% (n=578) needed family members to decide. The median time from confirmation of the EOL process to death and from the Advance Statement to death were 2 and 5 days, respectively (both ranges, 0 to 244). In total, 90% (n=727) of patients withheld treatment, and 10% (n=82)withdrew it. We found a higher withdrawal rate when family members made the decisions (13.3% vs. 1.7%, p < 0.001).ConclusionAfter the act’s enforcement, withdrawing LSTs became lawful and self-determination rates increased. Family members still make 71% of decisions regarding LSTs, but these are often inconsistent with the patients’ wishes; thus, further efforts are needed to integrate the new act into clinical practice.