The behavior of implanted nitrogen during post-implantation annealing has been studied at 400, 450, and 500 °C by depth profiling of 15N-implanted samples using the nuclear resonance broadening method. During the initial states of the annealing the nitrogen depth profiles behaved as if all the nitrogen would be able to diffuse, i.e., to be in solution, whereas for the longer annealing times the concentration of migrated nitrogen in the unimplanted region reached equilibrium with the implanted layer. The diffusion coefficients were determined as well as the equilibrium concentrations at the temperatures involved. The published values of the diffusion coefficients were extended to temperatures more than 500° C lower than before.