ObjectivesTo provide useful information for clinicians and policy makers to prepare guidelines for adequate use of medical resources during end-of-life period by analysing the intensive care use and related costs at the end of life in South Korea.DesignCross-sectional, retrospective, observational study.SettingTertiary hospitals in South Korea.ParticipantsWe analysed claim data and patient information from the Health Insurance Review and Assessment Service national dataset. This dataset included 19 119 older adults aged 65 years or above who received high-intensity care at least once and died in the intensive care unit in South Korea between 2016 and 2019. High-intensity care was defined as one of the following treatments or procedures: cardiopulmonary resuscitation, mechanical ventilation, extra-corporeal membrane oxygenation, haemodialysis, transfusion, chemotherapy and vasopressors.Primary and secondary outcome measuresUsage and cost of high-intensity care.ResultsThe most commonly used high-intensity care was transfusion (68.9%), mechanical ventilation (50.6%) and haemodialysis (35.7%) during the study period. The annual cost of high-intensity care at the end of life increased steadily from 2016 to 2019. There existed differences by age, gender, length of hospital stays and primary cause of death in use of high-intensity care and associated costs.ConclusionFindings indicate that invasive and device-dependent high-intensity care is frequently provided at the end of life among older adults, which could potentially place an economic burden on patients and their families. In Korea’s ageing society, increased rates of chronic illness are expected to significantly burden those who lack the financial resources to provide end-of-life care. Therefore, guidelines for the use of high-intensity care are required to ensure affordable end-of-life care.