Using the channeling method, implanted deuterium in niobium has been found to occupy a displaced tetrahedral site, in contrast to the normal tetrahedral site occupancy of dissolved deuterium. The comparison of experimental angular scans with computer simulations indicates that deuterium is displaced by about 0.02 nm towards the octahedral site. Moreover, the deuterium lattice site occupancy is found to depend upon the relaxation direction of the host lattice. The results are interpreted by taking into account the uniaxial distortion of the lattice parameter (up to 2%) within the implanted layer, as measured by channeling experiments.