The effect of radiation blistering on the retention of deuterium in the near‐surface region of 200‐keVd+irradiated Cu at 350 K has been studied. Blistering is detected using aninsitumethod based on the scattering of laser light. The incident deuteron beam is used both for implantation and to obtain the dynamic deuterium depth profile. Discrete blisters of approximately 4‐&mgr;m average diameter are found to form rapidly at a well‐defined fluence of (7±1) ×1018d+/cm2. The rate deuterium accumulates in the first 0.4 &mgr;m is found to fall dramatically at the onset of blistering from a steady value, of ∼2% of the implantation rate, to nearly zero. Typical D : Cu loadings at the critical dose for blistering are ∼1 at.%.