Background: This study aimed to explore the time interval distribution pattern between the Physicians Order for Life-Sustaining Treatment (POLST) form completion and death at a tertiary hospital in South Korea. It also examined the association between various independent parameters and POLST form completion timing. Methods: A total of 150 critically ill patients admitted to Korea University Guro Hospital between June 1, 2018 and December 31, 2018 who completed the POLST form were retrospectively analyzed and included in this study. Data were analyzed with descriptive statistics, and group comparisons were performed using the chi-square test for categorical variables. Fisher's exact test was also used to compare cancer versus non-cancer groups. Results: More than half the decedents (54.7%) completed their POLST within 15 days of death and 73.4% within 30 days. The non-cancer group had the highest percentage of patients (77.8%) who died within 15 days of POLST form completion while the colorectal (39.1%) and other cancer (37.5%) groups had the lowest (P=0.336). Conclusion: Our findings demonstrated a current need for more explicit guidance to assist physicians with initiating more timely, proactive end-of-life discussions.