We report the magnetic field splittings of emission lines assigned to the 5D 0- 7F 2 transitions of Eu centres in GaN. The application of a magnetic field in the c-axis direction (B∥c) leads to a splitting of the major lines at 621 nm, 622 nm and 622.8 nm into two components. The Zeeman splitting is linear with magnetic field up to 5 Tesla for each line. In contrast, a magnetic field applied in the growth plane (B⊥c) does not influence the photoluminescence spectra. The estimated g-factors vary slightly from sample to sample with mean values of g ∥ ∼2.8, ∼1.5 and ∼2.0 for the emission lines at 621 nm, 622 nm and 622.8 nm respectively. © 2011 Materials Research Society.