The properties of the cluster He_nV, an iron vacancy with an increasing number of He atoms, is studied with molecular statics and molecular dynamics simulations. A study of the binding energy of the self-interstitial atom (SIA) and the He, shows that from n = 6 the He_nV cluster is stable and cannot shrink anymore, and from n = 16 the He_nV₂ cluster is stabilized by the emission of SIA in the form of a〈110〉dumbbell. Calculation of the pressure exercised by the He_nV cluster shows local peak normal stress and shear stress values up to 9 GPa and 4 GPa, respectively. The local configurations of He_nV suggest that with increasing helium content, a high symmetry configuration close to a face centered cubic lattice is formed.