Clearly, a biotinylated biorecognition element can attach to streptavidin modified surface site-selectively have reported an immunosensor for the impedimetric detection of myelin basic protein. For this purpose, a polyaniline layer was deposited onto electrode surface electrochemically and then the biotin was immobilised onto the polymer. Following this, biotinylated surface was treated with avidin and then biotinylated antibodies were immobilised. Developed labelless impedimetric sensor was capable of detecting the antigen within the required physiological range.