We assessed the relation between BNP levels and some echocardiographic parameters of systolic and diastolic function of the left ventricle in 49 patients (mean age 69.39 +/- 8.47 years) with chronic kidney disease in different stages of chronic renal failure according to K/DOQI and in 45 subjects (mean age 52.6 +/- 14.85 years) on dialysis. Median for BNP in the group of patients with chronic renal failure was 132 pg/ml, and in dialysis subjects 320 pg/ml. None of our patients had clinical signs of heart failure during the last six months. Using a method of correlation matrix we found the left ventricular mass and its indexed value as a common indicator of increased BNP level in both groups of patients (dialysis patients, p = 0.0003, and p = 0.0005, respectively; patients with chronic renal failure, p = 0.03, and p = 0.04, respectively). Further analysis proved that in the group of dialysis patients the main determinants of increased BNP level were volumes of the left heart side: left ventricular end diastolic volume (p = 0.004), endsystolic volume (p = 0.01), and left atrial volumes (maximal, minimal, and total atrial stroke volume; p = 0.004, p = 0.009 and p = 0.04, respectively). In the group of patients with chronic renal failure the major contributors to increased BNP level were echocardiographic parameters of diastolic filling assessed from transmitral and pulmonary venous flow: E wave (p = 0.001), A wave (p = 0.01), E/A (p < 0.001), IVRT (p = 0.004), E/EDT (p < 0.0001), S wave (p = 0.01), D wave (p = 0.0003), S/D (p = 0.001), Ar duration (p = 0.02), and E/Vp (p = 0.003). No significant relation to left ventricular ejection fraction was found in both groups of patients. Our results suggest that the main determinant of increased BNP level in patients with different stages of chronic renal failure is diastolic dysfunction, whereas in dialysis patients high left heart volumes due to volume overload. The common denominator of high BNP level in both groups of patients is especially the left ventricular mass.