Objectives: Plasma BNP level also can be elevated in patients with renal insufficiency (RI) and diagnostic value was changes depending on the RI. The aim of this study was to evaluate the difference of diagnostic value for BNP according to the grade of renal insufficiency in systolic heart failure (SHF). Methods: Between Aug 2002 and June 2005, 328 patients who had SHF with RI were included. Heart failure was defined via using echocardiography and clinical criteria. We calculated creatinine clearance (Ccr) and defined RI as decreased Ccr (less than 90 mL/min). The severity of RI was graded by calculated Ccr in to 3 groups; mild 60���Ccr<90, moderate 30���Ccr<60, severe to end stage renal disease (ESRD) Ccr<30 mL/min. For cut-off value using an ROC curve, we compared to the patients with only RI, not SHF (n=281) during same period. Results: Mean age was 66짹12 and male was 61.4 %. Most common etiology was ischemia (37.2%). Mean Cr and Ccr levels were 1.74짹2.0 mg/dl, 50.3짹27.9 ml/min. There were not significant differences in sex, etiology, EF and LVEDD among each group except age. As renal function deteriorates, mean BNP level was elevated (see table). In patients with RI, significant negative correlation between BNP level and Ccr (r=-0.23, p=0.00) was noted. On the receiver operating characteristic curve, optimal cut-off point of BNP in diagnosing systolic HF in patients with RI was 729 pg/mL (accuracy 68 %, p=0.00). Especially, in case of moderate to severe RI patients, more significant negative correlation Ccr and higher cut-off value was noted (see table). Conclusions: As RI became severe, plasma BNP level became significantly higher. Especially, in case of patients with moderate to severe RI, we should consider higher cut-off point and relatively lower diagnostic accuracy of BNP.