The A-site cation diffusion in LaFeO3 has been examined by inter-diffusion experiments between LaFeO3 and NdFeO3. Dense, polycrystalline bodies were annealed in contact at temperatures between 1100 degrees and 1300 degrees C in ambient air. The bulk- and grain-boundary inter-diffusion coefficients were calculated from concentration profiles determined by electron probe micro analysis of cross sections. The bulk- and grain- boundary inter-diffusion coefficients showed Arrhenius-type behavior with activation energies 610 +/- 30 and 600 +/- 100 kJ/mol, respectively. Based on the assumption of 1 nm thick grain boundaries the grain- boundary inter-diffusion coefficient was similar to 4 orders of magnitude higher than the bulk inter-diffusion coefficient.