Sedation therapy is a potential solution to providing relief from refractory symptoms at end of life. The aim of this study was to investigate actual sedation practice and physician characteristics associated with the use of sedation for terminally ill cancer patients in South Korea. A retrospective review was conducted on consecutive patients who had died from cancer at seven tertiary medical centers between January 2010 and October 2015. The use of sedation was defined as the administration of sedative agents to relieve intolerable symptoms within the last 2 weeks preceding death. Patients and physician characteristics and information on the use of sedation were collected.A total of 8309 patients were included in the study. Sedatives were administered in 1334 patients (16.1%) for the following indications: delirium in 39.3%, intractable pain in 23.1%, and dyspnea in 21.9%. Median duration of sedation from initiation to death was 3 days. The use of sedation depended on physician specialty and experience. Family physicians used sedation most often (57.6%), followed by medical oncologists (13.9%), other internists (10.7%), and surgical oncologists (9.4%). The use of sedation was highest for physicians with >5 to 10 years practice experience (22.1%) and lowest for those in practice for 5 years or less (10.2%). The proportion of patients receiving sedation also varied markedly across participating institutions (range, 7.0%-49.7%).This large cohort study provides insight into sedation practice for terminally ill cancer patients in South Korea. Our study shows that the use of sedation depends on physician background and institution. A nation-wide guidelines and continued education on end-of-life sedation are required in South Korea.