An antiscattering grid for an X-ray imaging apparatus of the type comprising a substrate having a plurality of metallized partitions which together define a plurality of cells distributed over the substrate. The partitions allow passage of the X-rays emitted from a source lying in line with the grid, and absorbing the X-rays not coming directly from this source. The substrate is made of a polymer material that may be formed by radiation curing of a monomer sensitive to this radiation. The substrate may be substantially planar and the partitions may be oriented to form a focused grid.