The clinical presentation of right ventricular (RV) dysfunction due to congenital heart disease (CHD) is similar to that of cor pulmonale. RV volume and pressure loads, and primary RV myocardial dysfunction are mechanisms by which CHD affects right heart function. RV volume load may arise from pre-tricuspid left to right shunts (e.g., atrial septal defect) or regurgitant lesions in the right heart (e.g., Ebstein's anomaly of the tricuspid valve and pulmonary insufficiency after repair of tetralogy of Fallot). RV pressure load may be caused by anatomic obstruction to RV outflow and by pulmonary arteriolar hypertension. The latter can result from Eisenmenger syndrome secondary to congenital and postoperative left to right shunts or from defects that cause pulmonary venous hypertension (e.g., pulmonary vein stenosis, cor triatriatum, or mitral stenosis). The RV myocardium may be affected by a primary cardiomyopathy or by congenital abnormalities of the coronary vessels. Finally, CHD may be associated with airway obstruction, scoliosis, or pulmonary emboli, which, in turn, may lead to the development of cor pulmonale. Congenital heart disease, therefore, must be included in the differential diagnosis of patients who present with right ventricular dysfunction.