Objective To observe the characteristics of dipyridamole stress 201Tl SPECT myocardial imaging in adult patients with acute viral myocarditis, and to preliminarily explore its mechanism and clinical significance.Methods Four adults with acute viral myocarditis were chosen. Dipyridamole was administrated at 0.56mg/kg by intravenous injection within 4min. Images were acquired after 10min and 240min respectively.Three-dimensional reconstructions of the original images were analyzed by more than two experienced nuclear medicine physicians. Results In all of the four patients, three myocardial imagings showed the radioactive uniformity at stress stage but the radioactive defect at delayed stage in left ventriclar myocardium(one in inferior wall; one in apex, inferior and anterior wall; one in anterior wall),namely reverse redistribution. And the imaging of the other one showed the fixed radioactive defect in inferior wall both at stress and delayed stage. Conclusion Dipyridamole stress 201Tl SPECT myocardial imaging has certain value in the diagnosis of acute viral myocarditis of adults. The mechanism of reverse redistribution in dipyridamole stress 201Tl SPECT myocardial imaging is primarily relevant to the dysfunction of cardiac microcirculation.