A case of straddling mitral valve associated with double outlet right ventricle and coarctation of the aorta is presented. Radical operation (Jatene's procedure) was performed under the diagnosis of complete transposition of the great arteries associated with coarctation of the aorta. The patient could not survive the operation. Autopsy revealed that both of the great vessels originated in the right ventricle (double outlet right ventricle). In addition to this abnormality, some of the chordae of the mitral leaflet were attached to the right ventricular wall through the ventricular septal defect (straddling mitral valve). Echocardiograms recorded prior to the operation revealed feactures corresponding to the anatomical abnormalities, including that the anterior mitral leaflet moved far anterior to the ventricular septum. This is the first case of echocardiographic features of straddling mitral valve.