An improved device for the automatic feeding of silk screen printing machines with extension platens. The apparatus comprises:a storage magazine for the sheets to be printed, piled flat in a pile;structure associated with the printing platen and comprising a positioning support in an extension of the plane of this platen;apparatus to seize and transfer individual sheets from the pile onto the positioning support;frontal and lateral positioning structure for the sheet placed onto the positioning support; andpositioned sheet transfer apparatus to seize and transfer the sheet from the positioning support to the printing platen.