Age greater than or equal to 18 years

Current hospitalization for chronic congestive heart failure with admission up to 48 hours prior to randomization. Chronic heart failure is defined as requiring treatment for a minimum of 30 days prior to hospitalization. The subject must have signs of extracellular volume expansion, defined as two or more of the following: a) jugular venous distention; b) pitting edema (>1+); or c) dyspnea

NYHA Class III or IV at the time of hospitalization

Left Ventricular Ejection Fraction <= 40% within one year

Women who will not adhere to the reproductive precautions as outlined in the Informed Consent form

Positive urine pregnancy test

Inability to provide written informed consent

Cardiac surgery within 60 days of potential study enrollment, excluding percutaneous coronary interventions

Planned revascularization procedures, electrophysiologic (EP) device implantation, cardiac mechanical support implantation, cardiac transplantation, or other cardiac surgery within 30 days following study enrollment

Subjects who are on cardiac mechanical support

History of bi-ventricular pacer placement within the last 60 days

Co-morbid condition with an expected survival less than six months

Subjects with acute ST segment elevation myocardial infarction at the time of hospitalization

History of sustained ventricular tachycardia or ventricular fibrillation within 30 days, unless in the presence of an automatic implantable cardioverter defibrillator

History of a cerebrovascular accident within the last 30 days

Hemodynamically significant uncorrected primary cardiac valvular disease

Hypertrophic cardiomyopathy (obstructive or non-obstructive)

CHF due to uncorrected thyroid disease, active myocarditis or known amyloid cardiomyopathy

Subjects with progressive or episodic neurological disease such as multiple sclerosis or history of multiple strokes

History of primary significant liver disease or acute hepatic failure, as defined by the investigator

History of poorly controlled diabetes mellitus

Morbid obesity, defined as > 159 kg (or 350 lbs) or BMI > 40

Supine systolic arterial blood pressure < 90 mmHg

Serum creatinine > 3.5 mg/dL or > 309.4 mmol/L

Serum potassium > 5.5 mEq/L or > 5.5 mmol/L

Hemoglobin < 9 g/dL or < 90 g/L

History of hypersensitivity and/or idiosyncratic reaction to benzazepine derivatives (such as benazapril)

History of drug or medication abuse within the past year, or current alcohol abuse

Inability to take oral medications

Participation in another clinical drug or device trial within the past 30 days

Previous participation in this or any other tolvaptan clinical trial