The cw roentgenoluminescence and pulsed cathodoluminescence spectra of BeO ceramics doped with rare-earth (RE) oxides were studied at room and low temperatures. Oxygen deficiency was found to be the main factor influencing formation of luminescence centers in the BeO ceramic. The introduction of RE oxides promotes formation of additional oxygen vacancies in the surface layer of BeO microcrystals and leads to a 2.0-to 3.5-fold increase in the quantum yield of the intrinsic luminescence of BeO.