We have implanted ZnO thin film with 40 keV Fe+ ions to a high fluence of 1.25 x 10(17) ions/cm(2). Elemental and magnetic phase compositions were investigated by XRD, XPS, CEMS, and VSM methods. The Fe-implanted ZnO film reveals strong ferromagnetism at room temperature. The implanted iron ions are found in different valence states of Fe2+ and Fe3+. It was attributed to the formation of paramagnetic and ferromagnetic iron-based phases. The ferromagnetism is explained with the formation of a magnetic ordered solution of iron ions in ZnO matrix. Post-implantation annealing in a high vacuum results in the decrease of magnetism due to the formation of magnetite nanoparticles.