BACKGROUND: Current guidelines recommend the use of electrocardiography (ECG) in the evaluation of transient ischemic attack (TIA), but the data supporting its value in acute management are sparse. OBJECTIVE: To determine whether ECG findings are useful as independent predictors of short-term cardiac or neurologic complications after TIA. METHODS: We included patients who presented to 1 of 16 emergency departments of a health maintenance organization in northern California and received a diagnosis of TIA from March 1, 1997, through February 28, 1998, for a 90-day follow-up. A cardiac event was defined as a hospitalization or a death due to myocardial infarction, ventricular arrhythmia, heart failure, or unstable angina. RESULTS: Among the 1327 patients with TIA for whom ECG findings were available for diagnostic coding, cardiac events occurred in 2.9%, strokes in 10.9%, recurrent TIAs in 13.7%, and deaths in 2.6% during 90-day follow-up. The ECG findings disclosed a new diagnosis of atrial fibrillation in 28 (2.3%) of the 1200 patients with no history of this condition. The 90-day risk for a cardiac event was greater in those who had any abnormal ECG findings (4.2% vs 0.6%; P<.001). This association remained significant after adjustment for medical history and examination findings (odds ratio, 6.9; 95% confidence interval, 1.6-29.5; P =.009). Left ventricular hypertrophy, atrial fibrillation, and atrioventricular conduction abnormalities were each independently associated with more than doubling of the risk. The ECG abnormalities were not associated with risk for stroke or death. CONCLUSIONS: Short-term cardiac morbidity is substantial after TIA. Electrocardiographic findings disclose new atrial fibrillation in a significant portion of patients with TIA and can identify a group of patients at a substantially higher risk for short-term cardiac events.