The purposes of this study were to characterize the morphologic, imaging, and clinical characteristics of double-inlet, double-outlet right ventricle (DI-DORV), a rare congenital heart disease, and to compare these findings to those in patients with double-inlet left ventricle (DILV). The clinical records, imaging studies, and heart specimens of 22 consecutive patients with DI-DORV were reviewed. A comparison group of 44 patients with DILV was matched by age at latest follow-up. Among the 22 patients with DI-DORV, 14 had clinical data, 5 had clinical and autopsy data, and 3 had only autopsy data. Abdominal and atrial situs were normal in all, and heart position was levocardia in 91%. The morphology of the atrioventricular valves was variable, with 15 patients showing neither a typical tricuspid nor mitral valve. In the remaining 7 patients, 1 or both atrioventricular valves resembled a tricuspid or a mitral valve. Myocardial architecture was characterized by atypical muscle bundles of varying degrees of hypertrophy and orientation. Most patients had bilateral conus, and 82% had either aortic or pulmonary outflow tract obstructions. The rate of overall mortality or heart transplantation was 36%. Significant differences between DI-DORV and DILV included the type of ventricular loop, the type of conus, and a higher mortality rate in patients with DI-DORV. In conclusion, DI-DORV is a distinct type of functional single ventricle congenital heart disease with variable atrioventricular valve morphology and myocardial architecture. Accurate diagnosis using noninvasive imaging techniques is of paramount importance for optimal management.