This study investigated the perceptions and attitudes of ICU nurses towards the 'do not resuscitate' (DNR) decision and changes in their nursing activities after implementation of the DNR decision in South Korea. A data survey was conducted in South Korea between August and October 2008, with a convenience sample of 252 ICU nurses who had more than one year of clinical experience. The data were collected via a self-administered questionnaire. Most of the nurses perceived the necessity of the DNR decision in cases where there would be no chance of patient recovery despite massive efforts. Very few of the nurses' activities changed, either passively or actively, after implementation of the DNR decision. Moreover, the findings of this research provide suggestions for the future direction of the DNR decision and ethical nursing guidelines in South Korea. Further investigations are needed for the development of decision-making skills and intervention guidelines for end-of-life nursing.