The blue Mg induced 2.8 eV photoluminescence (PL) band in metalorganic chemical vapor deposition grown GaN has been studied in a large number of samples with varying Mg content. It emerges near a Mg concentration of1×1019 cm−3and at higher concentrations dominates the room temperature PL spectrum. The excitation power dependence of the 2.8 eV band provides convincing evidence for its donor–acceptor(D–A)pair recombination character. It is suggested that the acceptorAis isolatedMgGawhile the spatially separated, deep donor (430 meV)Dis attributed to a nearest-neighbor associate of aMgGaacceptor with a nitrogen vacancy, formed by self-compensation. ©1998 American Institute of Physics.