A primitive form of double-outlet right ventricle is described clinically and anatomically. A long tubular conus, arising exclusively from the right ventricle emptied into the transposed great vessels. Together with the presence of A-V canal malformation this heart represented a developmental arrest in the embryonic stage of the bulboventricular loop seen in horizon XV. Diagnosis is made on the basis of right ventricular angiography and theoretically, if this lesion is isolated, this conus malformation is surgically correctable.