The self-diffusion coefficient and the ionic conductivity in LaF₃ single crystals are measured over a temperature range from 300 to 1400K. Three thermally activated processes are found in this range. After heating, both the diffusion coefficient and the conductivity of the as-grown samples undergo strong irreversible changes at T<1100K. An activation energy of E_a=1.2eV and a Haven ratio of about 0.1 are determined in the intrinsic region. The mechanism of the ion transport and the effect of thermal treatment are discussed.