Thirteen patients with visceroatrial situs abnormalities were evaluated by magnetic resonance(MR) imaging. Eleven patients were confirmed surgically. Two patitnts were diagnosed by MRI and cardiac catheterization. Right isomerism was found in seven patients, left isomerism in two, and situs inversus in four. for the determination of situs, we evaluated the morphology of atrial appendages and main bronchi, the relationship between abdominal aorta and inferior vena cava (IVC), and the status of upper abdominal viscera. The bilateral atrial morphology was differentiated in 8 of 12 patients. The bronchial situs was determined in 11 of 12 patients. Juxtaposition of abdominal aorta and IVC was found in 6 of 7 with right isomerism. IVC interruption with azygos continuation was found in all two with left isomerism. Incidentally three cases of short pancreas were found. MR imaging showed all structures relevant for the assessment of situs, thus obvrating the need for performing additional diagnostic procedures. MR imaging, therefore, is a valuable tool in the clinical management of patients who are suspected of having a situs abnormality.