BACKGROUND AND OBJECTIVES: B-type natriuretic peptide (BNP) is released from the cardiac ventricles in response to increased wall tension. Early diagnosis of congestive heart failure (CHF) and assessment of the left ventricular end diastolic pressure (LVEDP) are thought to be important in the diagnosis, treatment and follow up of patients with CHF. SUBJECTS AND METHODS: Between March, 2002 and November, 2002, 50 patients, who were admitted for treatment and hemodynamic monitoring, were studied. For the BNP measurement, 3 to 5ml blood samples were collected into tubes containing EDTA. The BNP was measured with a fluorescence immunoassay kit (Triage, Biosite, San Diego, U.S.A.). Cardiac Catheterization was performed for the assessment of the LVEDP. RESULTS: Of the 50 subjects, 34 with CHF had a mean BNP level of 483.1+/-77.8 pg/mL, whereas those without CHF had a level of 79.2+/-24.0 pg/mL. The difference between the groups was statistically significant (p=0.005). A significant positive correlation was seen between the BNP and the LVEDP (r=0.53, p=0.001). The correlation between the BNP and the left ventricular ejection fraction (LVEF) was not statistically significant (r=-0.226, p=0.198). CONCLUSION: The plasma BNP was significantly increased in CHF, and might reflect the LVEDP. Further study will be required to see whether the BNP is a useful parameter for the staging and treatment of CHF.