We describe a new, direct electrochemical means of detecting biorecognition at modified electrodes. Ternary self-assembled monolayers (SAMs) were formed on gold electrodes by coadsorption of biotin, viologen, and oligo(ethylene glycol)-functionalized alkanethiols. These SAMs exhibit electroactivity of the viologen moieties, biospecificity of the biotin moieties, and inhibition of nonspecific adsorption by the oligo(ethylene glycol) moieties. Changes in electrochemical behavior of the immobilized viologen observed by cyclic voltammetry accompanying biospecific adsorption of an anti-biotin antibody to biotin can be used to transduce biorecognition on the surface rapidly and reproducibly. Surface plasmon resonance measurements are consistent with the electrochemical responses that result from the partially reversible adsorption of the antibody to the SAM surface.