There is described method of processing printed sheets (100), especially sheets of printed securities, into individual documents (150), such as banknotes, each printed sheet (100) comprising an array of imprints arranged in a matrix of rows and columns. The method comprises the following steps : (i) pre-processing the printed sheets (100) by partly slitting each printed sheet (100) row-wise or column-wise to form slits (110) between adjacent rows or adjacent columns of imprints, slitting being performed in such a manner that the adjacent rows or adjacent columns of imprints are still attached to one another at edges of each thus pre-processed printed sheet (100′); (ii) stacking the pre-processed printed sheets (100′) so as to form sheet stacks (121, 122) comprising a predetermined number of pre-processed printed sheets (100′) stacked one upon the other; and (iii) processing the sheet stacks (121, 122) by cutting each sheet stack (121, 122) column-wise or row-wise along cutting lines (115) between adjacent columns or rows of imprints, cutting being performed along a direction perpendicular to the direction of the slits (110) and in such a manner that individual documents (150) are produced as a result. Also described is a system for carrying out this method.