The ECG exercise stress test is a very potent aid to the clinical diagnosis of CAD. Thorough knowledge of the ECG abnormalities and clinical features related to the stress test are required for an accurate diagnosis. The ECG exercise stress test is not a substitute for clinical acumen. Proper evaluation of the stress test is a clinical art of the skilled clinician. ECG exercise stress testing can be done efficiently and effectively by trained emergency department physicians. As a result, the diagnosis of CAD can be greatly accelerated.