Background N-terminal pro-B-type natriuretic peptide (NT-proBNP) has recently been introduced as a useful marker for diagnosis and prognosis in various cardiac diseases. The purpose of this study is to evaluate the value of the NT-proBNP as a predictor of disease progression in patients with pericardial effusions. Methods We retrospectively studied consecutive patients who had moderate or large pericardial effusion with preserved left ventricular dysfunction from October 2004 to September 2006. Patients with reaccumulation of pericardial effusion after medical therapy or pericardiocentesis, persistent drainage of effusion through catheter longer than 1 week, or newly developed constrictive pericarditis were defined as progression group(Group I) and patients without these findings were defined as no progression group(Group II). NT-proBNP assay was performed when pericardial effusion was detected. Results Group I (n = 15) and Group II (n = 27) had similar baseline characteristics. Group I compared with Group II exhibited higher NT-proBNP(1063 짹 756 vs 578 짹 1090 ng/L, p = 0.002). The NT-proBNP was only independent predictor of disease progression(p = 0.036). A NT-proBNP value ���548 ng/L demonstrated a sensitivity of 80% and spefificity of 78% in identifying disease progression(p = 0.001)(Figure A & B). Conclusions the NT-proBNP value independently predicts disease progression in patients with pericardial effusions, but further prospective studies with more patients will be needed.