A particulate recording medium with an ultrathin magnetic layer is presented in this paper. This medium consists of a magnetic layer and a nonmagnetic underlayer composed of very fine titanium dioxide powder. When metal powder was employed, we observed the anticipated advantages of decreasing the thickness of the magnetic layer in tapes and diskettes. By reducing the layer thickness to below 0.3 µm we were able to increase the reproduced output at short wavelengths, and improve both the overwrite erasability and the D50. There was also a decrease in the half peak width of an isolated pulse and a peak shift. Tribological advantages were also observed with this medium. When barium ferrite was employed as the magnetic powder, we observed that the modulation noise of thin-layer barium ferrite medium was less than that of a thinlayer MP medium while it generated an output as high as that of the MP medium. The advantages of the barium ferrite medium lie in its two-layer construction. Particulate media will continue to develop as magnetic powder is improved mainly in terms of its size, saturation magnetization, and coercivity.