In this prospective study of 40 patients sustaining blunt chest trauma, the value of single-photon-emission computed tomography (SPECT)-thallium scanning in the prediction of morbidity due to cardiac contusion was examined. Twelve patients developed cardiac complications--arrhythmias, ventricular conduction defects, and pericarditis. The sensitivity of SPECT-thallium scans was 55.6%, and the specificity was 32.1%, with an accuracy of 37.8%. Accuracy of the initial electrocardiogram (ECG) was 85%, with a sensitivity of 91.7% and a specificity of 82.1%. Patients with a normal ECG on admission rarely developed cardiac complications. It is concluded that SPECT-thallium is not a useful screening tool in this patient population.