Surface damage of hot-rolled beryllium caused by 20 keV He + ions, at irradiation temperatures of 300 K (0.19 T m ) and 550 K (0.35 T m ), has been studied by optical microscopy. Total helium retention in the samples has been measured by proton backscattering and its depth profile has been obtained by a new variant of the Elastic Recoil Detection technique. At 300 K the micrographs reveal large blisters, with diameter ≈5 μm in as-received Be, and ≈10 μm when annealed (2 h at 923 K). Important helium reemission takes place slightly above the blistering threshold ( ≲3 × 10 17 He +/cm 2), and again at twice the threshold. The depth profiles are flattened, sometimes perhaps double-peaked, past the threshold. At 550 K, the samples (annealed) show severe exfoliation and repetitive blistering covering the whole surface. Sudden reemission of helium at a high rate (∼200% of incident flux) takes place slightly after blister appearance ( ≲2.5 × 10 17 He +/cm 2) and 100% reemission above ∼6 × 10 17 He +/cm 2. The profiles are flattened and wide. The observations suggest loss of helium coming from the center of the profiles, excluding migration to the surface through the superficial layer, and hence support the gas pressure model.