The geodetic datum, and its possible descriptions, of the Italian cadastral networks are analyzed, in order to provide a solution to fit the cadastral sheets to modern map contents and grids, using just their corner crosshair data. Analyzing the extension of the Genova 1902 datum to the whole Italian territory, it occured that the transformation error is acceptable only in the original survey area of the respective triangulation net. For Souther Italy and Sicily (Sicilia), the errors exceed the 20 meters. The Molodensky-type transformation parameters of the Castanea della Furie 1910 and the Guardia Vecchia (Sardinia) datums are provided using only their fundamental point coordinates, without error estimation. While these datums are not correctly checked at their whole application are, we suggest to define local datums of the Bessel ellipsoid, using the Bessel and WGS84coordinates of the respective cadastral grid origins and use them for geo-reference as a basis of the local Cassini grids.