Abstract In this paper, a structural analysis of Eurofer and ODS Eurofer was performed in terms of their radiation resistance. The radiation damage was simulated by helium ion implantation with kinetic energy of ions up to 500keV. The implanted ions reached the depth of about 1.2μm and the implantation dose was ∼1×1018ions/cm2. The radiation damage (∼45dpa) was investigated by suitable positron annihilation technique–Doppler broadening spectroscopy which showed visible accumulation of defects due to the implantation. According our results, ODS Eurofer seems to be more radiation resistant than classic Eurofer.