To compare modern, digital exercise echocardiography and thallium 201 single-photon emission computed tomography (SPECT) in patients with unstable coronary artery disease, 65 men unselected with regard to echocardiography were prospectively investigated 1 month after an episode of unstable angina or non-Q-wave myocardial infarction. Exercise echocardiography and 201Tl SPECT were performed on consecutive days in connection with a standard symptom-limited upright bicycle test and analyzed in a 9-segment model. Coronary angiography was performed in all but 1 patient and 60 patients had significant coronary lesions. Wall motion abnormalities were seen in 53 patients (81%) at rest and perfusion defects in 57 patients (88%) at the redistribution images. New or worsening of wall motion abnormalities were seen in 55 patients, either seated at peak exercise or recumbent after exercise, and 43 patients had reversible or partially reversible 201Tl scintigraphic defects (P = .02). The segmental agreement between wall motion abnormalities and scintigraphic defects was low (58%). The additional value of exercise echocardiography and 201Tl SPECT to exercise test was greatest in patients with one-vessel disease. Thus, 1 month after an episode of unstable coronary artery disease in men, there is a high incidence of significant coronary stenoses as well as signs of ischemia shown both by wall motion abnormalities during exercise echocardiography and by postexercise studies with 201Tl SPECT. Exercise echocardiography gives a higher diagnostic yield regarding occurrence of reversible ischemia.