Iron nanocubes with a diameter of about 200-400 nm were fabricated by reduction of ferrous sulfate with hydrazine in the solvent of ethylenediamine. During the reaction process, ethylenediamine acted as the solvent, complexant, and structure-directing agent, which was crucial for the formation of the cubes. Thus-prepared iron nanocubes exhibited a high saturation magnetism (Ms) of 690 emu/g, much superior to that of bulk or nanoparticulate counterpart.