We have developed a simple process to fabricate On a bioplatform patterns of nanoparticles of a molecule-based magnet. Nanoparticles of the ferromagnetic Prussian blue derivative CsxNi[Cr(CN)(6)] were orderly deposited onto S-layers of Lysinibacillus sphaericus, forming a dense carpet of nanopartides following the square lattice (p(4)) pattern of the biotemplate. These results are encouraging to extend this approach by focusing on molecule-based magnets patterned into domains with controlled shapes and positions on a biosurface.