Ultrathin rare earth oxide films have been fabricated using Langmuir-Blodgett films of rare earth arachidates as precursors. Irradiation of these films with UV light and subsequent heating of the films (350 degrees C) result in oxide films exhibiting a smoothness comparable to that of the Si-wafers used as substrates (roughness R approximate to 0.3 MI). The film thickness can easily be adjusted via the number of Langmuir-Blodgett monolayers deposited onto the substrate.