The effect of annealing under enhanced hydrostatic pressure (HT-HP treatment) on the structural evolution of nano-structured buried He-enriched layers in silicon was investigated by photoluminescence and TEM methods. It has been stated that the HT-HP treatment can affect the defect structure of nano-structured He-containing layer. Enhanced creation of helium bubbles during the HP-HT treatment takes place at HT £ 600oC. Annealing at HT ³ 800oC results in the accumulation (gettering) of oxygen atoms in the He implanted layer in Czochralski grown silicon. HP treatment stimulates this effect.