Right heart failure was produced in dogs by controlled progressive stenosis of the pulmonary artery. Cardiac enlargement, systemic venous engorgement, tachycardia, hepatomegaly and ascites were consistent findings. The course of cardiac failure was characterized by continual changes in cardiovascular hemodynamics; either cardiac decompensation became progressively severe or circulatory function improved and diuresis resulted. Sodium (Na) retention was always associated with high central venous pressure. Cardiac output was reduced during Na retention except during spontaneous anemia superimposed on cardiac failure. Glomerular filtration rate was frequently normal at the onset of cardiac failure.