Abstract: A security paper is provided for incorporation in a security document, or other document having intrinsic value. The security paper includes a resinous substrate sheet on which indicia are printed. Paper sheets are laminated on either side of the resinous substrate sheet using a suitable adhesive. In the laminated security paper, the indicia printed on the substrate sheet are undetectable when viewed in reflected light, but become apparent when viewed transmitted light within the visible spectrum. The security paper may be incorporated in a security document in which a set of indicia printed on at least one of the outer faces of the paper sheets, such that the indicia on the substrate and the indicia on the document form a total image when viewed in transmitted light. A method for manufacturing the security paper is also provided.