The energies characterizing helium migration and trapping in α-Al2O3have been calculated within the framework of the polarizable point-ion shell model developed for α-Al2O3. The helium self-energy, in the octahedral position, is 2.9 eV and the helium migration energy is 2.6 eV. If defects are present in α-Al2O3(arising, for example, from radiation damage) strong trapping of the helium occurs at oxygen vacancies (binding energy 1.7 eV) and at aluminum vacancies (binding energy 1.3 eV). The strong interaction with defects indicates that helium migration as well as the annealing of the defects are retarded by these trapping effects.