Radiation-induced defects in n-type GaN irradiated by 2 MeV electrons at room temperature were studied by electron paramagnetic resonance (EPR). Four EPR spectra, labelled D1-D4, were observed in irradiated n-type GaN. The D1 spectrum is a broad line (similar to 10-12 mT in line width) with an isotropic g-value g similar to 2.03 and can be detected in all the studied samples in the temperature range of 4-300 K. The D2 centre has an electron spin S = 1/2 and shows a clear hyperfine structure due to interaction with three equivalent N-14. The g-values of the axial configuration are determined to be g(parallel to) = 2.001 and g(perpendicular to) = 1.999. On the basis of the observed hyperfine structure, formation conditions and annealing behaviour, the D2 defect was assigned to the gallium vacancy-oxygen pair in the negative charge state, (VGaON)(-).