Forty-nine patients with atrial isomerism (right atrial isomerism 27, left atrial isomerism 22) diagnosed by 2DE of the abdominal great vessels were reported in this paper. Compared with the results of high kilovolt filtered chest film and autopsy, atrial situs determined by 2DE was concordant with bronchial morphology in 43 patients, 25 (93%) of right atrial isomerism, 18 (82%) of left isomerism. 25 patients who had angiocardiography or autopsy were associated with other cardiac malformations which were severe and complicated in right atrial isomerism. The results of this series showed that ultrasonography of the abdominal great vessels could be a reliable guide to the diagnosis of atrial isomerism, 2DE diagnosis is useful for angiocardiography.