Abstract: The present invention relates to masks for use in mass spectrometry, in particular MALDI, tissue section analysis, comprising a plate made of or coated by an opaque material and having a thickness of less than 150 ?m, said plate comprising regularly spaced openings, wherein in the plate upper plane, the diameter D of the largest circle comprising only one opening is superior to the diameter d of a mass spectrometer, in particular a MALDI analyzer, laser beam divided by sin ?, wherein ? is the mass spectrometer, in particular a MALDI analyzer, laser beam incidence angle with respect to the sample plane. The invention also concerns processes of manufacture of the masks according to the invention, the use thereof for mass spectrometry, in particular MALDI, imaging of tissue sections, and a method for MALDI imaging of a tissue section using said masks.