A method for the treatment of printing blocks made of zinc and copper, and their conservation is described. Individual workingprocesses are discussed, especially the degreasing, the removal of corrosion products from the block surface (for the zinc blocks by the amidosulphonic acid water solution and for the copper blocks by the water solution of the disodium salt of ethylenediamine tetraacetic acid with the additive of hydrazine sulfate in amrnonia solution), the surface treatment of blocks by the phosphatizing and chromatizing and the conservation of blocks by the protective layer of silicone oil, Lukooil MF or Lukooil 350. Author's address: National Museum, Natural Science Museum, 115 79 Praha 1, CSSR.