The invention relates to the mass spectrometry imaging of histologic thin tissue sections, where a mass spectrum is acquired for every image point. The invention provides a method for the identification and localization of proteins or other biomolecules of a histologic thin tissue section, comprising the following steps: a) the biomolecules of two similar thin tissue sections are enzymatically digested, substantially preserving the biomolecule positions in the tissue; b) a mass spectrometric image of the digest products in the first thin tissue section is acquired; c) the digest products of the second tissue section are extracted and separated with the aid of a separation method, and then introduced into a tandem mass spectrometer, which acquires mass spectra and daughter ion spectra of all the digest products present; d) a list of all identifiable biomolecules of the tissue is created by comparison of the mass spectra and daughter ion spectra of the digest products with spectra derived from biomolecule structure databases or correspondent spectral libraries; and e) the biomolecules in the list are assigned, on the basis of the masses of their digest products, to the digest products of the same mass in the mass spectra of the mass spectrometric image of the thin tissue section, after intelligent filtering, where necessary. With the aid of correlations of the mass-selective images, digest products can be identified as being wrongly assigned. The summation of well-correlating mass-selective images of the digest products of the biomolecules produces biomolecule-selective images, i.e. images of the distribution of the individual biomolecules in the thin tissue section.