Abstract Thermal release behavior of helium implanted into silver with 20 keV He + ions to fluences ranging from 5 × 10 20 to 5 × 10 21 ions/ m 2 has been studied. The number of release peaks increased and the initiating temperature for helium release became lower with increasing fluence. Above a fluence of 1.5 × 10 21 ions/ m 2, a significant release peak was observed around 550°C independently of fluence. It was ascertained that the activation energy for helium release in this peak was equivalent to that for the silver self-diffusion. The helium releasing mechanism was discussed, comparing the results for silver to those for copper and nickel.