The roentgenographic characteristics of 6 cases of Ebstein's anomaly of tricuspid valve were analyzed. The most remarkable feature on a plain film was a hugely enlarged heart shadow with a spherical configuration due to the marked dilatation of the right atrium. The infundibulum of the right ventricle was prominent and the pulmonary artery segment was depressed. There was diminished pulmonary vascularity with narrow vascular pedicle. On fluoroscopy and kymograph, except for the upper left border where vigorous pulsations existed, all parts of both cardiac borders showed much weakened pulsations. The angiographic findings of this group of patients were similar to those described in the textbooks or other references.A discussion was made on the differentiation of this anomaly from the tetralogy and trilogy of Fallot on plain films. The differentiation of Ebstein's anomaly from tetralogy was considered to be easy since the cardiac configurations of the two diseases are quite different. Three points were listed to be the differentiating criteria between Ebstein's anomaly and trilogy.In case the diagnosis of Ebstein's anomaly on plain films is not conclusive) or specific anatomical or hemodynamical abnormalities are required to be demonstrated, right cardiac catheterization and angiographic study should be performed.