Micromechanical cantilevers were validated for the detection of antibody peptide interactions. For this purpose, gold-coated microcantilevers were chemically functionalized with an analog of the myc-tag decapeptide. Chemoselective covalent coupling of the peptide to the gold surface occurred via the sulfhydryl- group of a C-terminal cystein residue. In order to verify the surface functionalization by epifluorescence microscopy, a carboxyfluorescein reporter group was attached to the N-terminus. Binding of an anti-myc-tag antibody caused a bending of the microcantilever, resulting from a change in surface stress. The bending was recorded optically from the deflection of a laser beam. In order to compensate for bending due to nonspecific interactions, a nonfunctionalized cantilever serving as a reference was measured in parallel. A charge coupled device camera served as a position-sensitive detector, enabling the parallel and simultaneous detection of signals from an array of microcantilevers. The results validate microcantilevers for the label-free detection of antibody peptide interactions at physiological solvent conditions. (C) 2003 American Vacuum Society.