Hole trap levels in a Mg-doped GaN grown by metalorganic vapor phase epitaxy (MOVPE) are studied with deep level transient spectroscopy (DLTS). The Mg concentration of the sample was4.8×1019 cm−3,but the hole concentration was as low as1.3×1017 cm−3at room temperature. The DLTS spectrum has a dominant peakD1with activation energy of0.41±0.05 eV,accompanied by two additional peaks with activation energies of0.49±0.09 eV(D2)and0.59±0.05 eV(D3).It was found that the dominant peakD1consists of five peaks, each of which has different activation energy and capture cross section. A relevant model for these levels is presented in relation to the Mg–N–H complexes. ©1998 American Institute of Physics.