We assessed the efficiency of non-specific extracorporeal immunoadsorption (EIA), using polyclonal anti-human immunoglobulin antibodies, in depleting the serum of anti-galactoseα1,3galactose (Gal) antibody and in decreasing serum cytotoxicity in 5 patients with idiopathic dilated cardiomyopathy. The mean concentrations of anti-Gal immunoglobulin (Ig)M and IgG before EIA were 74 μg/ml and 159 μg/ml, respectively. After EIA, these concentrations decreased by 86% and 88%, respectively. Both anti-Gal IgM and IgG returned to pre-EIA concentrations within 1 month, without rebound to greater than baseline concentrations. After EIA, mean serum cytotoxicity also decreased from 90% to 17%, with recovery by 1 month. Extracorporeal immunoadsorption proved safe in patients with heart failure and was effective in depleting anti-Gal antibody and in decreasing serum cytotoxicity to pig cells.