The higher stress associated with the World Trade Center (WTC) attacks on September 11, 2001, may have resulted in more cardiac events particularly in those living in close proximity. Our goal was to determine if there was an increase in cardiac events in a subset of emergency departments (EDs) within a 50-mi radius of the WTC. We performed a retrospective analysis of consecutive patients seen by ED physicians in 16 EDs for the 60 days before and after September 11 in 2000-2002. We determined the number of patients admitted to an inpatient bed with a primary or secondary diagnosis of acute myocardial infarction (MI) or tachyarrhythmia. In each year, we compared patient visits for the 60 days before and after September 11 using the chi-square statistic. For the 360 days during the 3 years, there were 571,079 patient visits in the database of which 110,766 (19.4%) were admitted. Comparing the 60 days before and after September 11, 2001, we found a statistically significant increase in patients with MIs (79 patients before versus 118 patients after, P =.01), representing an increase of 49%. There were no statistically significant differences for MIs in 2000 and 2002 and in tachyarrhythmias for all three years. For the 60-day period after September 11, 2001, we found a statistically significant increase in the number of patients presenting with acute MI but no increase in patients admitted with tachyarrhythmias.