Immunoadsorption (IA) represents an additional therapeutic approach in patients with severe heart failure due to dilated cardiomyopathy (DCM). nt-BNP and nt-ANP plasma levels are prognostic markers in patients with heart failure. The effect of IA on nt-BNP and nt-ANP plasma levels is unknown. In this case control study, 30 patients suffering from severe heart failure (LVEF < 35%) due to DCM were included. In 15 patients, IA was carried out in four courses of monthly intervals until month 3. For analysis of the acute and prolonged effects, the plasma levels of nt-BNP and nt-ANP were determined before and after each IA course. In 15 comparable DCM patients (controls), plasma levels of nt-BNP and nt-ANP were determined at baseline and after 3 months. LVEF remained stable during this study in the control group. In contrast, in the IA group after 3 months, LVEF increased from 29.7 +/- 1 to 38.6 +/- 2%, P < 0.001. In the control group, the nt-BNP and nt-ANP plasma levels remained stable during the 3 months of the study. In the IA group after the first IA course, the level of nt-BNP was acutely reduced from 1501 +/- 328 to 925 +/- 151 fmol/mL, P < 0.01. In addition, the nt-ANP level was reduced from 4439 +/- 1271 to 2897 +/- 825 fmol/mL, P < 0.01. In the IA group, the reduction of these two parameters remained detectable after 3 months before the last course: nt-BNP: 714 +/- 119 fmol/mL, nt-ANP: 2227 +/- 427 fmol/mL, P < 0.05. The improvement of left ventricular function during IA is accompanied by a reduction of nt-BNP and nt-ANP plasma levels in patients with DCM.