Single crystals of iron-implanted TiO2 rutile have been investigated by the electron paramagnetic resonance (EPR) technique at room temperature. The spectra have been interpreted to correspond to the transitions among the spin multiplet (S = 5/2, L = 0) of the paramagnetic Fe3+ ions. Analysis of the EPR spectra shows that iron in TiO2 rutile host substitutes for Ti4+ ions. Two equivalent Fe3+ centers have been observed in the EPR spectra in correspondence with two equivalent octahedral positions of the Ti ions in the rutile structure. Parameters of the crystal field of orthorhombic symmetry on the Fe3+ centers have been obtained as a result of computer modelling. (c) 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.