End-of- life care is a major issue in medical ethics with life support technology progress. Intensive care may prolong the dying process in patients who have been unresponsive to the treatment already provided. Withholding or withdrawing of life support (WLS) care was introduced to avoid the suffering of critically ill patients. Decision to WLS is a difficult and affected by several factors including not only disease severity but also ethics, religion, culture, and legal background. In western countries, advance directives had an important role to WLS for dying patients and honor patient autonomy. However, the illegality of advance directives in Korea and Korean culture under Confucianism, requiring children to do the best to treat their parents in the name of filial piety make physicians and family members difficult to WLS in terminally ill patients.