The effects of interface roughness on the amplitudes of Fowler-Nordheim (FN) tunneling current oscillations in ultrathin metal-oxide-semiconductor field transistors are investigated by numerical analysis. The interface roughness is described in terms of Gauss distribution. The amplitudes of FN tunneling current oscillations in ultrathin gate oxides are shown to decrease much with SiO2-Si interface roughness increasing. The factor of attenuation amplitudes increases exponentially with SiO2-Si interface roughness increasing. This means that the changes in amplitudes and the factors of attenuation amplitudes may be used to extract the information about the interface roughness.