Patients who present to the emergency room diagnosed with acute decompensated heart failure requiring the administration of intravenous diuretics and found to have normal contractile function will be eligible for participation in this study. Patients must have pulmonary congestion documented on their admitting chest X-ray and clinical evidence of volume overload such as rales or edema on physical examination at the time of randomization. Patients will have received at least one dose of IV Furosemide either in-route to the emergency room or on presentation to the emergency room. An echocardiogram will be obtained after presentation to the emergency room documenting a normal (>50%) left ventricular ejection fraction. Patients will be randomized to Natrecor or placebo in addition to a standard medical therapy. Study drug will be administered for 24 hours. Study drug will be initiated with a 2-µg/kg loading bolus followed by .01-µg/kg/min infusion. This may be increased at a rate of .005-µg/kg/min. every 3 hours until maximum dose of .03-µg/kg/min. Any increase in the infusion rate will be preceded by a 1-µg/kg bolus and increases in infusion rates will be permitted only in patients who have a systolic blood pressure > 100 mmHg. IV Nitroglycerin and IV Milrinone will be prohibited within 2 hours prior to initiating study drug infusion to three hours after completion of study drug infusion. All other intravenous vasoactive medications including other IV inotropes will be avoided within 2 hours prior to initiating study drug infusion to three hours after start of study drug infusion. Oral ACE inhibitors will be avoided from 2 hours prior to initiating study drug infusion to 30 minutes after start of study drug so as to avoid potential hypotension. Concomitant 'standard of care medications' including diuretics (IV or PO), ACE inhibitors, Aldactone, Digoxin etc. will be left to investigator discretion to be administered during the hospital stay as indicated. The primary endpoint of this study will be an absolute reduction in brain natriuretic peptide (BNP) levels three hours after discontinuation of the study drug. BNP is elevated in acute decompensated heart failure and has utility in outcome, severity and prognosis of patients with ADHF .