We present a complex study of rare earth elements implanted GaN layers grown by low pressure metalorganic vapor phase epitaxy on c-plane sapphire substrates. Gd, Dy, La and Lu ions were implanted with energies of 200 key and doses ranging from 5 x 10(13) to 4 x 10(17) atoms.cm(-2). The chemical composition and concentration profiles of ion-implanted layers were studied by secondary ion mass spectrometry and Rutherford back scattering. The structural properties of the layers were characterized by Rutherford back scattering/channeling and X-ray diffraction reciprocal space mapping. Gd implanted layers exhibit ferromagnetic behavior persisting up to similar to 720 K. Since the ferromagnetic behavior was not observed in the case of La and Lu implanted layers, it cannot be attributed to the structural damage of the layer. Based on the fact that the samples are electrically conducting we conclude that the ferromagnetism can be associated with doped electrons mediating the ferromagnetic interaction between local moments on Gd and Dy. (C) 2011 Elsevier B.V. All rights reserved.