The properties of charge-compensated Fe 3+ centers in hydrothermally grown ZnO single crystals were investigated by electron paramagnetic resonance (EPR) in X-and Q-band. The EPR angular dependences of the three types of Fe 3+ centers were fitted using spin Hamiltonians appropriate for S= 5 2 centers with C i symmetry. The analysis of the results, and in particular the determination of the second rank fine structure tensors, suggests that Fe 3+ substitutes Zn 2+ with a significant distortion of the initial C 3v symmetry of the Zn site. The centers are interpreted as Fe 3+ substitutional on the Zn site with (i) an oxygen vacancy in one of the nearest non-axial anionic positions,(ii) a Zn vacancy in one of the six positions lying in the basal plane and (iii) a Zn vacancy in one of the nearest six cationic positions which form a trigonal prism.