Congenitally corrected transposition (CCT) of the great vessels is an uncommon anomaly usually detected in children because of associated severe cardiac malformations. When these are absent, patients may be hemodynamically normal, but associated cardiac abnormalities are usually present in CCT, leading to symptoms in adulthood. When CCT is suggested in an adult, diagnosis by means of ultrasound may be difficult. Radionuclide angiocardiography (RA) is a simple, noninvasive method by which to diagnose CCT. We found consistent morphologic scintigraphic results in 13 patients with proved CCT, leading to establishment of reliable diagnostic criteria. In all instances of situs solitus the aorta ascends and descends on the left with vertical orientation. In the case of situs inversus, the aorta ascends and descends on the right with vertical orientation. Our criteria are independent of the situs and cardiac position, unlike earlier reports by others. We believe images obtained in the anterior projection are sufficient for the study. The practical application of RA study in patient diagnosis is demonstrated, giving special attention to patients referred because of situs solitus and dextrocardia, in which CCT is known to be present in 50% of cases.