The publication of comprehensive evidence-based guidelines for the management of non-ST-segment elevation acute coronary syndrome by the American College of Cardiology and the American Heart Association in September 2000 marked a sentinel event in the evolution of managing this challenging patient population. Many of the recommendations included in the guidelines have relevance to the emergency department care of patients with non-ST-segment elevation acute coronary syndrome and were summarized in Annals of Emergency Medicine in September 2001. New clinical data in this area continue to accumulate at a remarkably rapid rate, prompting the American College of Cardiology and the American Heart Association to publish an update of the 2000 guidelines in October 2002. Several of the modified and new recommendations again potentially affect ED management. These are presented and discussed here.