The magnetic properties of the epitaxial Mg and Mn co-doped GaN films with low Mg and Mn concentrations grown by plasma-enhanced molecular beam epitay (PEMBE) are reported. Surface morphology was smoother as Mn effusion cell temperature increased. Room-temperature ferromagnetic ordering was observed. The saturation magnetization (M-s) of the films increased as Mn effusion cell temperature (T-Mn) increased. Saturation magnetization change was not observed with the variation of Mg effusion cell temperature, and this supports that Mg incorporation in the films is not related to ferromagnetic ordering in the films. The samples exhibit n-type conductivity with the room-temperature ferromagnetism, and the films' characteristics are determined by Mn flux at fixed growth temperature. (C) 2003 Elsevier B.V. All rights reserved.