The room temperature mechanical properties of unirradiated hot and cold isostatically pressed high purity beryllium and Zircaloy-2 are compared in three-point bend tests. For ram displacement rates of 1 mm min⁻¹ beryllium exhibits comparable ductility (outer fibre strain) to that obtained with Zircaloy. However, for faster ram displacement rates (6.25 mm s⁻¹) the beryllium specimen fractured in an elastic manner. Fast (E > 1 MeV) neutron irradiation of a beryllium specimen at 350 K to a fluence of 6.44 × 10²⁴ n m⁻² results in a negative growth strain of 0.03% and a loss in ductility. No visible radiation damage was detected by transmission electron microscopy and the observed irradiation growth strain is attributed to the formation of submicroscopic defect clusters.