The contribution of precipitating protons to the formation of the duskside auroral oval is examined. Auroral images at wavelengths of 5577 ¿ (O1) and 4861 ¿ (H&bgr;) are compared with auroral particle data obtained by the DMSP F6 and F7 satellites. On the basis of the particle data, we found a proton-dominant region in which the input energy carried by protons exceeded that of electrons. The proton-dominant region is located at the equatorward edge of the duskside auroral oval. A direct comparison of data from auroral photoemissions and auroral particle precipitations reveals that the region of diffuse 5577 ¿ and 4861 ¿ auroras equatorward of the quiet discrete arcs coincides with the proton-dominant region. Furthermore, we found a spot-like structure of the proton aurora drifting westward at a speed of 0.4 km/sec. ¿American Geophysical Union 1987