Abstract: In a method for checking filters for permeability, in particular for the presence of leaks or other faulty zones which have increased permeability in comparison with other filter zones for particles to be filtered from an air or gas stream, air or gas charged with such particles as applied to one surface of the filter and the other side of the filter is scanned with an indicator system indicating the penetration of particles. The method is arranged in such manner that zonewise scanning of the reverse filter surface takes place by means of a suction nozzle, that upon entrance of a particle flow into the suction nozzle a measuring device arranged in the flow path is separately influenced by the particle flow for each scanned region, and that the result for each scanned region emitting a particle flow is indicated separately.