Langmuir-Blodgett (LB) films of polyaniline (PANI) were utilized for the fabrication of impedimetric immunosensor for detection of human plasma low density lipoprotein (LDL) by immobilizing anti-apolipoprotein B (AAB) via EDC-NHS coupling. The modified electrodes were characterized by electrochemical impedance spectroscopy (EIS) and scanning electron microscopy. AAB/PANI-SA LB immunoelectrodes studied by EIS spectroscopy revealed detection of LDL in the wide range of 0.018 mu m (6 mg/dl) to 0.39 mu M (130 mg/dl), covering the physiological range in blood, with a sensitivity of 11.25 k Omega mu M(-1) (C) 2010 Elsevier B.V. All rights reserved.