Evidence for chemically-induced anisotropy in antibody Langmuir-Blodgett films fixed with glutaraldehyde is reported. It has been found, by means of the nanogravimetric technique and surface potential measurements, that fixing each antibody monolayer prevents molecular reorientation during and after deposition onto a solid substrate, and results in the appearance of a -150 mV surface potential which quenches the antibody layer-fixative reaction.