Software was developed to find automatically the maximum electrostatic similarity between biomolecules by varying the relative positions and the conformations of one of them. This similarity is defined by means of the Spearman correlation coefficient computed over the molecular electrostatic potential (MEP) values at points of a volume around the molecules. Several tests are presented, including a comparison between 1-methyl-4-phenyl-1,2,5,6-tetrahydropyridine (MPTP) and benzylamine (BZA), two substrates of monoamine oxidase B (MAO-B). The proposed algorithm can be useful for molecular modelling and quantitative structure-activity relationship (QSAR) studies. © 1991.