Add to ORKGWe have studied structural transformations in pre-damaged GaAs crystals irradiated with high-energy Bi ions (710 MeV, 4.3 x 1012cm-2). The pre-damage has been created via irradiation with swift electrons (4 MeV, 4 x 1017cm-2). A structural disorder in irradiated samples has been investigated by means of selective chemical etching (SCE) and X-ray diffraction (XRD) in combination with the material layer-by-layer removal. Character of lattice deformation in the double-irradiated sample gives an evidence of subsurface region’s swelling. Strong lattice distortion has been found in the region of Bi ion ranges at the depth of about 30 lm. The nature of this effect is discusse